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>

mitra_app/lib/main.dart

@@ -2,6 +2,7 @@ import 'package:firebase_core/firebase_core.dart';
 import 'package:firebase_messaging/firebase_messaging.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 import 'core/api/api_client.dart';
 import 'core/auth/auth_bloc.dart';
@@ -20,7 +21,7 @@ void main() async {
   final messaging = FirebaseMessaging.instance;
   await messaging.requestPermission();
 
-  runApp(const App());
+  runApp(const ProviderScope(child: App()));
 }
 
 class App extends StatefulWidget {