- Add languageProvider (StateProvider<String>, default 'ru') with
supportedLanguages map matching backend locale.Supported
- Wire Accept-Language header into AuthInterceptor via languageGetter
callback; all API requests now carry the current language
- Sync language from user profile preferences into languageProvider
on every ProfileNotifier load/update
- Add language field to UpdateProfileRequest, serialized as
preferences.language in PUT /profile
- Profile screen: НАСТРОЙКИ section displays current language;
edit sheet adds DropdownButtonFormField for language selection
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>