feat(l10n): 캐릭터 생성 화면 하드코딩 텍스트 l10n 적용

- newCharacterTitle, soldButton 키 추가 (app_en.arb, app_ko.arb)
- new_character_screen.dart 하드코딩 텍스트를 L10n 함수로 변경
- 관련 테스트 업데이트 (widget_test.dart, new_character_screen_test.dart)

변경 내역:
- "Progress Quest - New Character" → L10n.newCharacterTitle
- "Sold!" → L10n.soldButton

lib/l10n/app_en.arb

@@ -242,5 +242,11 @@
     "placeholders": {
       "percent": { "type": "int" }
     }
-  }
+  },
+
+  "newCharacterTitle": "ASCII-Nara - New Character",
+  "@newCharacterTitle": { "description": "New character screen title" },
+
+  "soldButton": "Sold!",
+  "@soldButton": { "description": "Confirm character creation button" }
 }

lib/l10n/app_ko.arb

@@ -71,5 +71,7 @@
   "roll": "굴리기",
   "race": "종족",
   "classTitle": "직업",
-  "percentComplete": "{percent}% 완료"
+  "percentComplete": "{percent}% 완료",
+  "newCharacterTitle": "아스키나라 - 새 캐릭터",
+  "soldButton": "확인!"
 }

lib/src/features/new_character/new_character_screen.dart

@@ -200,7 +200,7 @@ class _NewCharacterScreenState extends State<NewCharacterScreen> {
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
-        title: const Text('Progress Quest - New Character'),
+        title: Text(L10n.of(context).newCharacterTitle),
         centerTitle: true,
       ),
       body: SingleChildScrollView(
@@ -231,7 +231,7 @@ class _NewCharacterScreenState extends State<NewCharacterScreen> {
             FilledButton.icon(
               onPressed: _onSold,
               icon: const Icon(Icons.check),
-              label: const Text('Sold!'),
+              label: Text(L10n.of(context).soldButton),
               style: FilledButton.styleFrom(
                 padding: const EdgeInsets.symmetric(vertical: 16),
               ),

test/features/new_character_screen_test.dart

@@ -19,8 +19,8 @@ void main() {
       _buildTestApp(NewCharacterScreen(onCharacterCreated: (_) {})),
     );
 
-    // 화면 타이틀 확인
+    // 화면 타이틀 확인 (l10n 적용됨)
-    expect(find.text('Progress Quest - New Character'), findsOneWidget);
+    expect(find.text('ASCII-Nara - New Character'), findsOneWidget);
 
     // 종족 섹션 확인
     expect(find.text('Race'), findsOneWidget);

test/widget_test.dart

@@ -14,8 +14,8 @@ void main() {
     await tester.tap(find.text('New character'));
     await tester.pumpAndSettle();
 
-    // NewCharacterScreen으로 이동했는지 확인
+    // NewCharacterScreen으로 이동했는지 확인 (l10n 적용됨)
-    expect(find.text('Progress Quest - New Character'), findsOneWidget);
+    expect(find.text('ASCII-Nara - New Character'), findsOneWidget);
     expect(find.text('Race'), findsOneWidget);
     expect(find.text('Class'), findsOneWidget);
     expect(find.text('Sold!'), findsOneWidget);