feat(theme): 다크 테마를 레트로 RPG 스타일로 변경

- RetroColors 색상 팔레트 적용
- PressStart2P 폰트를 헤더/라벨에 적용
- 앱바, 버튼, 다이얼로그, 칩 등 전체 테마 통일
- 프로그레스 인디케이터 골드 색상 적용

lib/src/app.dart

@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 import 'package:askiineverdie/data/game_text_l10n.dart' as game_l10n;
 import 'package:askiineverdie/l10n/app_localizations.dart';
 import 'package:askiineverdie/src/core/audio/audio_service.dart';
+import 'package:askiineverdie/src/shared/retro_colors.dart';
 import 'package:askiineverdie/src/core/engine/game_mutations.dart';
 import 'package:askiineverdie/src/core/engine/progress_service.dart';
 import 'package:askiineverdie/src/core/engine/reward_service.dart';
@@ -102,22 +103,131 @@ class _AskiiNeverDieAppState extends State<AskiiNeverDieApp> {
     useMaterial3: true,
   );
 
-  /// 다크 테마 (OLED 저전력 모드 - 순수 검정)
+  /// 다크 테마 (레트로 RPG 스타일)
   ThemeData get _darkTheme => ThemeData(
-    colorScheme: ColorScheme.dark(
-      surface: Colors.black,
-      primary: const Color(0xFF4FC3F7), // 시안
-      secondary: const Color(0xFFFF4081), // 마젠타
-      onSurface: Colors.white70,
-      primaryContainer: const Color(0xFF1A3A4A),
-      onPrimaryContainer: Colors.white,
-    ),
-    scaffoldBackgroundColor: Colors.black,
+    colorScheme: RetroColors.colorScheme,
+    scaffoldBackgroundColor: RetroColors.deepBrown,
     useMaterial3: true,
-    // 카드/다이얼로그도 검정 배경 사용
-    cardColor: const Color(0xFF121212),
-    dialogTheme: const DialogThemeData(
-      backgroundColor: Color(0xFF121212),
+    // 카드/다이얼로그 레트로 배경
+    cardColor: RetroColors.panelBg,
+    dialogTheme: DialogThemeData(
+      backgroundColor: RetroColors.panelBg,
+      titleTextStyle: const TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 12,
+        color: RetroColors.gold,
+      ),
+    ),
+    // 앱바 레트로 스타일
+    appBarTheme: AppBarTheme(
+      backgroundColor: RetroColors.darkBrown,
+      foregroundColor: RetroColors.textLight,
+      titleTextStyle: const TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 12,
+        color: RetroColors.gold,
+      ),
+    ),
+    // 버튼 테마
+    filledButtonTheme: FilledButtonThemeData(
+      style: FilledButton.styleFrom(
+        backgroundColor: RetroColors.buttonPrimary,
+        foregroundColor: RetroColors.textLight,
+        textStyle: const TextStyle(
+          fontFamily: 'PressStart2P',
+          fontSize: 10,
+        ),
+      ),
+    ),
+    outlinedButtonTheme: OutlinedButtonThemeData(
+      style: OutlinedButton.styleFrom(
+        foregroundColor: RetroColors.gold,
+        side: const BorderSide(color: RetroColors.gold, width: 2),
+        textStyle: const TextStyle(
+          fontFamily: 'PressStart2P',
+          fontSize: 10,
+        ),
+      ),
+    ),
+    textButtonTheme: TextButtonThemeData(
+      style: TextButton.styleFrom(
+        foregroundColor: RetroColors.cream,
+        textStyle: const TextStyle(
+          fontFamily: 'PressStart2P',
+          fontSize: 10,
+        ),
+      ),
+    ),
+    // 텍스트 테마
+    textTheme: const TextTheme(
+      headlineLarge: TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 18,
+        color: RetroColors.gold,
+      ),
+      headlineMedium: TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 14,
+        color: RetroColors.gold,
+      ),
+      headlineSmall: TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 12,
+        color: RetroColors.gold,
+      ),
+      titleLarge: TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 12,
+        color: RetroColors.textLight,
+      ),
+      titleMedium: TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 10,
+        color: RetroColors.textLight,
+      ),
+      titleSmall: TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 8,
+        color: RetroColors.textLight,
+      ),
+      bodyLarge: TextStyle(fontSize: 14, color: RetroColors.textLight),
+      bodyMedium: TextStyle(fontSize: 12, color: RetroColors.textLight),
+      bodySmall: TextStyle(fontSize: 10, color: RetroColors.textLight),
+      labelLarge: TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 10,
+        color: RetroColors.textLight,
+      ),
+      labelMedium: TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 8,
+        color: RetroColors.textLight,
+      ),
+      labelSmall: TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 6,
+        color: RetroColors.textLight,
+      ),
+    ),
+    // 칩 테마
+    chipTheme: ChipThemeData(
+      backgroundColor: RetroColors.panelBgLight,
+      labelStyle: const TextStyle(
+        fontFamily: 'PressStart2P',
+        fontSize: 8,
+        color: RetroColors.textLight,
+      ),
+      side: const BorderSide(color: RetroColors.panelBorderInner),
+    ),
+    // 리스트 타일 테마
+    listTileTheme: const ListTileThemeData(
+      textColor: RetroColors.textLight,
+      iconColor: RetroColors.gold,
+    ),
+    // 프로그레스 인디케이터
+    progressIndicatorTheme: const ProgressIndicatorThemeData(
+      color: RetroColors.gold,
+      linearTrackColor: RetroColors.panelBorderOuter,
     ),
   );