feat(localization): Implement Swedish localization and error messages

- Added localization support for Swedish and English languages.
- Integrated localized strings for user messages in the API error mapper.
- Updated UI components to use localized strings for labels and messages.
- Ensured all error messages are context-aware and utilize the localization framework.
- Created regression test to prevent common ASCII fallbacks in Swedish UI text.

flutter/lib/features/auth/data/auth_repository.dart

@@ -19,7 +19,7 @@ class AuthRepository {
       if (data is! Map<String, dynamic>) {
         throw const ApiException(
           type: ApiErrorType.unknown,
-          message: 'Ogiltigt svar fran servern.',
+          message: 'Ogiltigt svar från servern.',
         );
       }
 
@@ -38,7 +38,7 @@ class AuthRepository {
     } catch (_) {
       throw const ApiException(
         type: ApiErrorType.network,
-        message: 'Kunde inte na servern.',
+        message: 'Kunde inte nå servern.',
       );
     }
   }