refactor(ui): 화면 및 위젯 정리

- GamePlayScreen build() 메서드 분할 (300→15 LOC)
- 애니메이션/프로그레스 패널 개선
- 설정 화면 정리

lib/src/core/notification/notification_service.dart

@@ -1,5 +1,7 @@
 import 'dart:async';
 
+import 'package:asciineverdie/data/game_text_l10n.dart' as game_l10n;
+
 /// 알림 타입 (Notification Type)
 enum NotificationType {
   levelUp, // 레벨업
@@ -62,8 +64,8 @@ class NotificationService {
     show(
       GameNotification(
         type: NotificationType.levelUp,
-        title: 'LEVEL UP!',
-        subtitle: 'Level $newLevel',
+        title: game_l10n.notifyLevelUp,
+        subtitle: game_l10n.notifyLevel(newLevel),
         data: {'level': newLevel},
         duration: const Duration(seconds: 2),
       ),
@@ -75,7 +77,7 @@ class NotificationService {
     show(
       GameNotification(
         type: NotificationType.questComplete,
-        title: 'QUEST COMPLETE!',
+        title: game_l10n.notifyQuestComplete,
         subtitle: questName,
         data: {'quest': questName},
         duration: const Duration(seconds: 2),
@@ -87,8 +89,8 @@ class NotificationService {
   /// actNumber: 0=프롤로그, 1=Act I, 2=Act II, ...
   void showActComplete(int actNumber) {
     final title = actNumber == 0
-        ? 'PROLOGUE COMPLETE!'
-        : 'ACT $actNumber COMPLETE!';
+        ? game_l10n.notifyPrologueComplete
+        : game_l10n.notifyActComplete(actNumber);
     show(
       GameNotification(
         type: NotificationType.actComplete,
@@ -103,7 +105,7 @@ class NotificationService {
     show(
       GameNotification(
         type: NotificationType.newSpell,
-        title: 'NEW SPELL!',
+        title: game_l10n.notifyNewSpell,
         subtitle: spellName,
         data: {'spell': spellName},
         duration: const Duration(seconds: 2),
@@ -116,7 +118,7 @@ class NotificationService {
     show(
       GameNotification(
         type: NotificationType.newEquipment,
-        title: 'NEW EQUIPMENT!',
+        title: game_l10n.notifyNewEquipment,
         subtitle: equipmentName,
         data: {'equipment': equipmentName, 'slot': slot},
         duration: const Duration(seconds: 2),
@@ -129,7 +131,7 @@ class NotificationService {
     show(
       GameNotification(
         type: NotificationType.bossDefeat,
-        title: 'BOSS DEFEATED!',
+        title: game_l10n.notifyBossDefeated,
         subtitle: bossName,
         data: {'boss': bossName},
         duration: const Duration(seconds: 3),