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/pubspec.yaml

@@ -11,10 +11,13 @@ dependencies:
     sdk: flutter
   flutter_web_plugins:
     sdk: flutter
+  flutter_localizations:
+    sdk: flutter
   go_router: ^14.0.0
   riverpod: ^2.5.1
   flutter_riverpod: ^2.5.1
   http: ^1.2.1
+  intl: any
   shared_preferences: ^2.2.3
 
 dev_dependencies:
@@ -25,3 +28,4 @@ dev_dependencies:
 
 flutter:
   uses-material-design: true
+  generate: true