feat(ui): 화면 및 공통 위젯 개선

- FrontScreen 개선
- GamePlayScreen, GameSessionController 업데이트
- ArenaBattleScreen, NewCharacterScreen 정리
- AsciiDisintegrateWidget 추가

lib/src/features/game/game_play_screen.dart

@@ -1181,6 +1181,7 @@ class _GamePlayScreenState extends State<GamePlayScreen>
                 state.progress.currentCombat?.monsterStats.hpCurrent,
             monsterHpMax: state.progress.currentCombat?.monsterStats.hpMax,
             monsterName: state.progress.currentCombat?.monsterStats.name,
+            monsterLevel: state.progress.currentCombat?.monsterStats.level,
           ),
 
           // Experience 바