feat: 다국어 지원 및 다중 통화 환율 변환 기능 확대

- ExchangeRateService에 JPY, CNY 환율 지원 추가
- 구독 서비스별 다국어 표시 이름 지원
- 분석 화면 차트 및 UI/UX 개선
- 설정 화면 전면 리팩토링
- SMS 스캔 기능 사용성 개선
- 전체 앱 다국어 번역 확대

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

lib/providers/navigation_provider.dart

@@ -4,7 +4,7 @@ class NavigationProvider extends ChangeNotifier {
   int _currentIndex = 0;
   final List<int> _navigationHistory = [0];
   String _currentRoute = '/';
-  String _currentTitle = '홈';
+  String _currentTitle = 'home';
 
   int get currentIndex => _currentIndex;
   List<int> get navigationHistory => List.unmodifiable(_navigationHistory);
@@ -28,10 +28,10 @@ class NavigationProvider extends ChangeNotifier {
   };
 
   static const Map<int, String> indexToTitle = {
-    0: '홈',
-    1: '분석',
-    3: 'SMS 스캔',
-    4: '설정',
+    0: 'home',
+    1: 'analysis',
+    3: 'smsScanLabel',
+    4: 'settings',
   };
 
   void updateCurrentIndex(int index, {bool addToHistory = true}) {
@@ -39,7 +39,7 @@ class NavigationProvider extends ChangeNotifier {
     
     _currentIndex = index;
     _currentRoute = indexToRoute[index] ?? '/';
-    _currentTitle = indexToTitle[index] ?? '홈';
+    _currentTitle = indexToTitle[index] ?? 'home';
     
     if (addToHistory && index >= 0) {
       _navigationHistory.add(index);
@@ -57,17 +57,17 @@ class NavigationProvider extends ChangeNotifier {
     
     if (index >= 0) {
       _currentIndex = index;
-      _currentTitle = indexToTitle[index] ?? '홈';
+      _currentTitle = indexToTitle[index] ?? 'home';
     } else {
       switch (route) {
         case '/add-subscription':
-          _currentTitle = '구독 추가';
+          _currentTitle = 'addSubscription';
           break;
         case '/subscription-detail':
-          _currentTitle = '구독 상세';
+          _currentTitle = 'subscriptionDetail';
           break;
         default:
-          _currentTitle = '홈';
+          _currentTitle = 'home';
       }
     }
     
@@ -89,7 +89,7 @@ class NavigationProvider extends ChangeNotifier {
   void reset() {
     _currentIndex = 0;
     _currentRoute = '/';
-    _currentTitle = '홈';
+    _currentTitle = 'home';
     _navigationHistory.clear();
     _navigationHistory.add(0);
     notifyListeners();
@@ -98,7 +98,7 @@ class NavigationProvider extends ChangeNotifier {
   void clearHistoryAndGoHome() {
     _currentIndex = 0;
     _currentRoute = '/';
-    _currentTitle = '홈';
+    _currentTitle = 'home';
     _navigationHistory.clear();
     _navigationHistory.add(0);
     notifyListeners();