fix: 修复语言设置为简体中文而非繁体翻译

apps/lib/app/app.dart

@@ -379,8 +379,10 @@ class _EryaoAppState extends State<EryaoApp> {
   }
 
   Future<void> _bootstrap() async {
-    final localeCode = await _sessionStore.getLocaleCode();
-    final locale = localeCode == 'en' ? const Locale('en') : const Locale('zh');
+    final localeTag = await _sessionStore.getLocaleTag();
+    final locale = localeTag != null
+        ? localeFromLanguageTag(localeTag)
+        : const Locale('zh');
     if (mounted) {
       setState(() {
         _locale = locale;
@@ -392,7 +394,7 @@ class _EryaoAppState extends State<EryaoApp> {
 
   Future<void> _handleInterfaceLanguageChanged(String languageTag) async {
     final locale = localeFromLanguageTag(languageTag);
-    await _sessionStore.saveLocaleCode(locale.languageCode);
+    await _sessionStore.saveLocaleTag(languageTag);
     if (!mounted) {
       return;
     }