feat(settings): 설정 화면 및 저장소 추가

- SettingsScreen 구현 (테마, 언어, 사운드, 애니메이션 속도)
- SettingsRepository에 BGM/SFX 볼륨, 애니메이션 속도 저장 추가
- 설정 관련 l10n 텍스트 추가 (한/영/일)

lib/data/game_text_l10n.dart

@@ -1792,3 +1792,97 @@ String get uiLoading {
   if (isJapaneseLocale) return '読み込み中...';
   return 'Loading...';
 }
+
+// ============================================================================
+// 설정 화면 텍스트
+// ============================================================================
+
+String get uiSettings {
+  if (isKoreanLocale) return '설정';
+  if (isJapaneseLocale) return '設定';
+  return 'Settings';
+}
+
+String get uiTheme {
+  if (isKoreanLocale) return '테마';
+  if (isJapaneseLocale) return 'テーマ';
+  return 'Theme';
+}
+
+String get uiThemeLight {
+  if (isKoreanLocale) return '라이트';
+  if (isJapaneseLocale) return 'ライト';
+  return 'Light';
+}
+
+String get uiThemeDark {
+  if (isKoreanLocale) return '다크';
+  if (isJapaneseLocale) return 'ダーク';
+  return 'Dark';
+}
+
+String get uiThemeSystem {
+  if (isKoreanLocale) return '시스템';
+  if (isJapaneseLocale) return 'システム';
+  return 'System';
+}
+
+String get uiLanguage {
+  if (isKoreanLocale) return '언어';
+  if (isJapaneseLocale) return '言語';
+  return 'Language';
+}
+
+String get uiSound {
+  if (isKoreanLocale) return '사운드';
+  if (isJapaneseLocale) return 'サウンド';
+  return 'Sound';
+}
+
+String get uiBgmVolume {
+  if (isKoreanLocale) return 'BGM 볼륨';
+  if (isJapaneseLocale) return 'BGM音量';
+  return 'BGM Volume';
+}
+
+String get uiSfxVolume {
+  if (isKoreanLocale) return '효과음 볼륨';
+  if (isJapaneseLocale) return '効果音音量';
+  return 'SFX Volume';
+}
+
+String get uiAnimationSpeed {
+  if (isKoreanLocale) return '애니메이션 속도';
+  if (isJapaneseLocale) return 'アニメーション速度';
+  return 'Animation Speed';
+}
+
+String get uiSpeedSlow {
+  if (isKoreanLocale) return '느림';
+  if (isJapaneseLocale) return '遅い';
+  return 'Slow';
+}
+
+String get uiSpeedNormal {
+  if (isKoreanLocale) return '보통';
+  if (isJapaneseLocale) return '普通';
+  return 'Normal';
+}
+
+String get uiSpeedFast {
+  if (isKoreanLocale) return '빠름';
+  if (isJapaneseLocale) return '速い';
+  return 'Fast';
+}
+
+String get uiAbout {
+  if (isKoreanLocale) return '정보';
+  if (isJapaneseLocale) return '情報';
+  return 'About';
+}
+
+String get uiAboutDescription {
+  if (isKoreanLocale) return 'Progress Quest 6.4를 Flutter로 재구현한 오프라인 싱글플레이어 RPG입니다.';
+  if (isJapaneseLocale) return 'Progress Quest 6.4をFlutterで再実装したオフラインシングルプレイヤーRPGです。';
+  return 'An offline single-player RPG reimplementation of Progress Quest 6.4 in Flutter.';
+}

lib/src/core/storage/settings_repository.dart

@@ -3,10 +3,13 @@ import 'package:shared_preferences/shared_preferences.dart';
 
 /// 앱 설정 저장소 (SharedPreferences 기반)
 ///
-/// 테마, 언어 등 사용자 설정을 로컬에 저장
+/// 테마, 언어, 사운드 등 사용자 설정을 로컬에 저장
 class SettingsRepository {
   static const _keyThemeMode = 'theme_mode';
   static const _keyLocale = 'locale';
+  static const _keyBgmVolume = 'bgm_volume';
+  static const _keySfxVolume = 'sfx_volume';
+  static const _keyAnimationSpeed = 'animation_speed';
 
   SharedPreferences? _prefs;
 
@@ -49,4 +52,40 @@ class SettingsRepository {
     await init();
     return _prefs!.getString(_keyLocale);
   }
+
+  /// BGM 볼륨 저장 (0.0 ~ 1.0)
+  Future<void> saveBgmVolume(double volume) async {
+    await init();
+    await _prefs!.setDouble(_keyBgmVolume, volume.clamp(0.0, 1.0));
+  }
+
+  /// BGM 볼륨 불러오기 (기본값: 0.7)
+  Future<double> loadBgmVolume() async {
+    await init();
+    return _prefs!.getDouble(_keyBgmVolume) ?? 0.7;
+  }
+
+  /// SFX 볼륨 저장 (0.0 ~ 1.0)
+  Future<void> saveSfxVolume(double volume) async {
+    await init();
+    await _prefs!.setDouble(_keySfxVolume, volume.clamp(0.0, 1.0));
+  }
+
+  /// SFX 볼륨 불러오기 (기본값: 0.8)
+  Future<double> loadSfxVolume() async {
+    await init();
+    return _prefs!.getDouble(_keySfxVolume) ?? 0.8;
+  }
+
+  /// 애니메이션 속도 저장 (0.5 ~ 2.0, 1.0이 기본)
+  Future<void> saveAnimationSpeed(double speed) async {
+    await init();
+    await _prefs!.setDouble(_keyAnimationSpeed, speed.clamp(0.5, 2.0));
+  }
+
+  /// 애니메이션 속도 불러오기 (기본값: 1.0)
+  Future<double> loadAnimationSpeed() async {
+    await init();
+    return _prefs!.getDouble(_keyAnimationSpeed) ?? 1.0;
+  }
 }

lib/src/features/settings/settings_screen.dart

@@ -0,0 +1,412 @@
+import 'package:flutter/material.dart';
+
+import 'package:askiineverdie/data/game_text_l10n.dart' as game_l10n;
+import 'package:askiineverdie/src/core/storage/settings_repository.dart';
+
+/// 통합 설정 화면
+///
+/// 언어, 테마, 사운드, 애니메이션 속도 등 모든 설정을 한 곳에서 관리
+class SettingsScreen extends StatefulWidget {
+  const SettingsScreen({
+    super.key,
+    required this.settingsRepository,
+    required this.currentThemeMode,
+    required this.onThemeModeChange,
+    this.onLocaleChange,
+  });
+
+  final SettingsRepository settingsRepository;
+  final ThemeMode currentThemeMode;
+  final void Function(ThemeMode mode) onThemeModeChange;
+  final void Function(String locale)? onLocaleChange;
+
+  @override
+  State<SettingsScreen> createState() => _SettingsScreenState();
+
+  /// 설정 화면을 모달 바텀시트로 표시
+  static Future<void> show(
+    BuildContext context, {
+    required SettingsRepository settingsRepository,
+    required ThemeMode currentThemeMode,
+    required void Function(ThemeMode mode) onThemeModeChange,
+    void Function(String locale)? onLocaleChange,
+  }) {
+    return showModalBottomSheet<void>(
+      context: context,
+      isScrollControlled: true,
+      useSafeArea: true,
+      builder: (context) => DraggableScrollableSheet(
+        initialChildSize: 0.7,
+        minChildSize: 0.5,
+        maxChildSize: 0.95,
+        expand: false,
+        builder: (context, scrollController) => SettingsScreen(
+          settingsRepository: settingsRepository,
+          currentThemeMode: currentThemeMode,
+          onThemeModeChange: onThemeModeChange,
+          onLocaleChange: onLocaleChange,
+        ),
+      ),
+    );
+  }
+}
+
+class _SettingsScreenState extends State<SettingsScreen> {
+  double _bgmVolume = 0.7;
+  double _sfxVolume = 0.8;
+  double _animationSpeed = 1.0;
+  bool _isLoading = true;
+
+  @override
+  void initState() {
+    super.initState();
+    _loadSettings();
+  }
+
+  Future<void> _loadSettings() async {
+    final bgm = await widget.settingsRepository.loadBgmVolume();
+    final sfx = await widget.settingsRepository.loadSfxVolume();
+    final speed = await widget.settingsRepository.loadAnimationSpeed();
+
+    if (mounted) {
+      setState(() {
+        _bgmVolume = bgm;
+        _sfxVolume = sfx;
+        _animationSpeed = speed;
+        _isLoading = false;
+      });
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+
+    if (_isLoading) {
+      return const Center(child: CircularProgressIndicator());
+    }
+
+    return Container(
+      decoration: BoxDecoration(
+        color: theme.scaffoldBackgroundColor,
+        borderRadius: const BorderRadius.vertical(top: Radius.circular(16)),
+      ),
+      child: Column(
+        children: [
+          // 핸들 바
+          Container(
+            margin: const EdgeInsets.only(top: 8),
+            width: 40,
+            height: 4,
+            decoration: BoxDecoration(
+              color: theme.colorScheme.onSurface.withValues(alpha: 0.3),
+              borderRadius: BorderRadius.circular(2),
+            ),
+          ),
+          // 헤더
+          Padding(
+            padding: const EdgeInsets.all(16),
+            child: Row(
+              children: [
+                Icon(Icons.settings, color: theme.colorScheme.primary),
+                const SizedBox(width: 8),
+                Text(
+                  game_l10n.uiSettings,
+                  style: theme.textTheme.titleLarge,
+                ),
+                const Spacer(),
+                IconButton(
+                  icon: const Icon(Icons.close),
+                  onPressed: () => Navigator.of(context).pop(),
+                ),
+              ],
+            ),
+          ),
+          const Divider(height: 1),
+          // 설정 목록
+          Expanded(
+            child: ListView(
+              padding: const EdgeInsets.all(16),
+              children: [
+                // 테마 설정
+                _buildSectionTitle(game_l10n.uiTheme),
+                _buildThemeSelector(),
+                const SizedBox(height: 24),
+
+                // 언어 설정
+                _buildSectionTitle(game_l10n.uiLanguage),
+                _buildLanguageSelector(),
+                const SizedBox(height: 24),
+
+                // 사운드 설정
+                _buildSectionTitle(game_l10n.uiSound),
+                _buildVolumeSlider(
+                  label: game_l10n.uiBgmVolume,
+                  value: _bgmVolume,
+                  icon: Icons.music_note,
+                  onChanged: (value) {
+                    setState(() => _bgmVolume = value);
+                    widget.settingsRepository.saveBgmVolume(value);
+                  },
+                ),
+                const SizedBox(height: 8),
+                _buildVolumeSlider(
+                  label: game_l10n.uiSfxVolume,
+                  value: _sfxVolume,
+                  icon: Icons.volume_up,
+                  onChanged: (value) {
+                    setState(() => _sfxVolume = value);
+                    widget.settingsRepository.saveSfxVolume(value);
+                  },
+                ),
+                const SizedBox(height: 24),
+
+                // 애니메이션 속도
+                _buildSectionTitle(game_l10n.uiAnimationSpeed),
+                _buildAnimationSpeedSlider(),
+                const SizedBox(height: 24),
+
+                // 정보
+                _buildSectionTitle(game_l10n.uiAbout),
+                _buildAboutCard(),
+              ],
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+
+  Widget _buildSectionTitle(String title) {
+    return Padding(
+      padding: const EdgeInsets.only(bottom: 8),
+      child: Text(
+        title,
+        style: Theme.of(context).textTheme.titleMedium?.copyWith(
+          fontWeight: FontWeight.bold,
+        ),
+      ),
+    );
+  }
+
+  Widget _buildThemeSelector() {
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.all(8),
+        child: Row(
+          children: [
+            _buildThemeOption(
+              icon: Icons.light_mode,
+              label: game_l10n.uiThemeLight,
+              mode: ThemeMode.light,
+            ),
+            _buildThemeOption(
+              icon: Icons.dark_mode,
+              label: game_l10n.uiThemeDark,
+              mode: ThemeMode.dark,
+            ),
+            _buildThemeOption(
+              icon: Icons.brightness_auto,
+              label: game_l10n.uiThemeSystem,
+              mode: ThemeMode.system,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _buildThemeOption({
+    required IconData icon,
+    required String label,
+    required ThemeMode mode,
+  }) {
+    final isSelected = widget.currentThemeMode == mode;
+    final theme = Theme.of(context);
+
+    return Expanded(
+      child: InkWell(
+        onTap: () => widget.onThemeModeChange(mode),
+        borderRadius: BorderRadius.circular(8),
+        child: Container(
+          padding: const EdgeInsets.symmetric(vertical: 12),
+          decoration: BoxDecoration(
+            color: isSelected
+                ? theme.colorScheme.primaryContainer
+                : Colors.transparent,
+            borderRadius: BorderRadius.circular(8),
+          ),
+          child: Column(
+            children: [
+              Icon(
+                icon,
+                color: isSelected
+                    ? theme.colorScheme.primary
+                    : theme.colorScheme.onSurface,
+              ),
+              const SizedBox(height: 4),
+              Text(
+                label,
+                style: TextStyle(
+                  fontSize: 12,
+                  fontWeight: isSelected ? FontWeight.bold : FontWeight.normal,
+                  color: isSelected
+                      ? theme.colorScheme.primary
+                      : theme.colorScheme.onSurface,
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+
+  Widget _buildLanguageSelector() {
+    final currentLocale = game_l10n.currentGameLocale;
+    final languages = [
+      ('en', 'English', '🇺🇸'),
+      ('ko', '한국어', '🇰🇷'),
+      ('ja', '日本語', '🇯🇵'),
+    ];
+
+    return Card(
+      child: Column(
+        children: languages.map((lang) {
+          final isSelected = currentLocale == lang.$1;
+          return ListTile(
+            leading: Text(lang.$3, style: const TextStyle(fontSize: 24)),
+            title: Text(lang.$2),
+            trailing: isSelected
+                ? Icon(Icons.check, color: Theme.of(context).colorScheme.primary)
+                : null,
+            onTap: () {
+              game_l10n.setGameLocale(lang.$1);
+              widget.settingsRepository.saveLocale(lang.$1);
+              widget.onLocaleChange?.call(lang.$1);
+              setState(() {});
+            },
+          );
+        }).toList(),
+      ),
+    );
+  }
+
+  Widget _buildVolumeSlider({
+    required String label,
+    required double value,
+    required IconData icon,
+    required void Function(double) onChanged,
+  }) {
+    final theme = Theme.of(context);
+    final percentage = (value * 100).round();
+
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+        child: Row(
+          children: [
+            Icon(
+              value == 0 ? Icons.volume_off : icon,
+              color: theme.colorScheme.primary,
+            ),
+            const SizedBox(width: 12),
+            Expanded(
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Row(
+                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                    children: [
+                      Text(label),
+                      Text('$percentage%'),
+                    ],
+                  ),
+                  Slider(
+                    value: value,
+                    onChanged: onChanged,
+                    divisions: 10,
+                  ),
+                ],
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _buildAnimationSpeedSlider() {
+    final theme = Theme.of(context);
+    final speedLabel = switch (_animationSpeed) {
+      <= 0.6 => game_l10n.uiSpeedSlow,
+      >= 1.4 => game_l10n.uiSpeedFast,
+      _ => game_l10n.uiSpeedNormal,
+    };
+
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+        child: Row(
+          children: [
+            Icon(Icons.speed, color: theme.colorScheme.primary),
+            const SizedBox(width: 12),
+            Expanded(
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Row(
+                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                    children: [
+                      Text(game_l10n.uiAnimationSpeed),
+                      Text(speedLabel),
+                    ],
+                  ),
+                  Slider(
+                    value: _animationSpeed,
+                    min: 0.5,
+                    max: 2.0,
+                    divisions: 6,
+                    onChanged: (value) {
+                      setState(() => _animationSpeed = value);
+                      widget.settingsRepository.saveAnimationSpeed(value);
+                    },
+                  ),
+                ],
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _buildAboutCard() {
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.all(16),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Text(
+              'ASCII NEVER DIE',
+              style: Theme.of(context).textTheme.titleMedium,
+            ),
+            const SizedBox(height: 8),
+            Text(
+              game_l10n.uiAboutDescription,
+              style: Theme.of(context).textTheme.bodySmall,
+            ),
+            const SizedBox(height: 8),
+            Text(
+              'v1.0.0',
+              style: Theme.of(context).textTheme.bodySmall?.copyWith(
+                color: Theme.of(context).colorScheme.outline,
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}