feat(audio): 화면들 채널별 SFX API 적용

- game_play_screen: playPlayerSfx/playMonsterSfx 분리 사용
- settings_screen: 오디오 설정 UI 개선

lib/src/features/settings/settings_screen.dart

@@ -13,6 +13,8 @@ class SettingsScreen extends StatefulWidget {
     required this.currentThemeMode,
     required this.onThemeModeChange,
     this.onLocaleChange,
+    this.onBgmVolumeChange,
+    this.onSfxVolumeChange,
   });
 
   final SettingsRepository settingsRepository;
@@ -20,6 +22,12 @@ class SettingsScreen extends StatefulWidget {
   final void Function(ThemeMode mode) onThemeModeChange;
   final void Function(String locale)? onLocaleChange;
 
+  /// BGM 볼륨 변경 콜백 (AudioService 연동용)
+  final void Function(double volume)? onBgmVolumeChange;
+
+  /// SFX 볼륨 변경 콜백 (AudioService 연동용)
+  final void Function(double volume)? onSfxVolumeChange;
+
   @override
   State<SettingsScreen> createState() => _SettingsScreenState();
 
@@ -30,6 +38,8 @@ class SettingsScreen extends StatefulWidget {
     required ThemeMode currentThemeMode,
     required void Function(ThemeMode mode) onThemeModeChange,
     void Function(String locale)? onLocaleChange,
+    void Function(double volume)? onBgmVolumeChange,
+    void Function(double volume)? onSfxVolumeChange,
   }) {
     return showModalBottomSheet<void>(
       context: context,
@@ -45,6 +55,8 @@ class SettingsScreen extends StatefulWidget {
           currentThemeMode: currentThemeMode,
           onThemeModeChange: onThemeModeChange,
           onLocaleChange: onLocaleChange,
+          onBgmVolumeChange: onBgmVolumeChange,
+          onSfxVolumeChange: onSfxVolumeChange,
         ),
       ),
     );
@@ -147,6 +159,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
                   onChanged: (value) {
                     setState(() => _bgmVolume = value);
                     widget.settingsRepository.saveBgmVolume(value);
+                    widget.onBgmVolumeChange?.call(value);
                   },
                 ),
                 const SizedBox(height: 8),
@@ -157,6 +170,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
                   onChanged: (value) {
                     setState(() => _sfxVolume = value);
                     widget.settingsRepository.saveSfxVolume(value);
+                    widget.onSfxVolumeChange?.call(value);
                   },
                 ),
                 const SizedBox(height: 24),
@@ -241,7 +255,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
               Icon(
                 icon,
                 color: isSelected
-                    ? theme.colorScheme.primary
+                    ? theme.colorScheme.onPrimaryContainer
                     : theme.colorScheme.onSurface,
               ),
               const SizedBox(height: 4),
@@ -251,7 +265,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
                   fontSize: 12,
                   fontWeight: isSelected ? FontWeight.bold : FontWeight.normal,
                   color: isSelected
-                      ? theme.colorScheme.primary
+                      ? theme.colorScheme.onPrimaryContainer
                       : theme.colorScheme.onSurface,
                 ),
               ),