refactor(game): 게임 페이지 및 로컬라이제이션 정리

- GamePlayScreen 개선
- CharacterSheetPage 정리
- StoryPage 단순화
- 로컬라이제이션 정리

lib/src/features/game/pages/character_sheet_page.dart

@@ -105,11 +105,9 @@ class CharacterSheetPage extends StatelessWidget {
   }
 
   Widget _buildExpBar(BuildContext context) {
-    final localizations = L10n.of(context);
     final progress = exp.max > 0
         ? (exp.position / exp.max).clamp(0.0, 1.0)
         : 0.0;
-    final remaining = exp.max - exp.position;
 
     return Padding(
       padding: const EdgeInsets.all(12),
@@ -123,7 +121,7 @@ class CharacterSheetPage extends StatelessWidget {
           ),
           const SizedBox(height: 4),
           Text(
-            '$remaining ${localizations.xpNeededForNextLevel}',
+            '${exp.position} / ${exp.max}',
             style: TextStyle(fontSize: 10, color: Colors.grey.shade600),
           ),
         ],