Phase 3.1 WIP: Riverpod migration (client_app Auth + ChatOpening)

- Add phase3.1 requirement and implementation plan docs
- Add Riverpod dependencies to both client_app and mitra_app
- Wrap both app roots with ProviderScope
- Migrate client_app AuthBloc → AuthNotifier (@riverpod annotation)
- Migrate client_app ChatOpeningBloc → chatPricingProvider (FutureProvider)
- Update router to use Riverpod-based auth state for redirects
- Update all auth screens (display name, register, OTP, force register)
- Update home screen and pricing bottom sheet
- Add android:usesCleartextTraffic for dev HTTP access on both apps
- mitra_app prepared with ProviderScope + ApiClient provider (blocs next)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

client_app/pubspec.yaml

@@ -27,6 +27,10 @@ dependencies:
   # State management
   flutter_bloc: ^8.1.5
   equatable: ^2.0.5
+  flutter_riverpod: ^2.6.1
+  hooks_riverpod: ^2.6.1
+  riverpod_annotation: ^2.6.1
+  flutter_hooks: ^0.20.5
 
   # Storage
   shared_preferences: ^2.2.3
@@ -39,6 +43,10 @@ dev_dependencies:
   flutter_test:
     sdk: flutter
   flutter_lints: ^3.0.0
+  riverpod_generator: ^2.6.2
+  build_runner: ^2.4.13
+  custom_lint: ^0.7.0
+  riverpod_lint: ^2.6.2
 
 flutter:
   uses-material-design: true