Phase 2 refinements: Firebase config, dev environment fixes, phase 3 requirement draft

- Integrated Firebase SDK in both Flutter apps (google-services, firebase_options)
- Fixed auth flow, API client, and pairing/status blocs for dev environment
- Added full Flutter project scaffolds (android, ios, web, etc.)
- Added phase 3 chat engine requirement document
- Added bugreport zip pattern to gitignore

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

mitra_app/lib/core/chat/chat_request_bloc.dart

@@ -92,11 +92,7 @@ class ChatRequestBloc extends Bloc<ChatRequestEvent, ChatRequestState> {
   }
 
   void _listenToSSE() {
-    final dio = Dio(BaseOptions(baseUrl: ApiClient.baseUrl));
-    dio.get(
-      '/api/mitra/chat-requests/incoming',
-      options: Options(responseType: ResponseType.stream),
-    ).then((response) {
+    apiClient.getStream('/api/mitra/chat-requests/incoming').then((response) {
       final stream = response.data.stream as Stream<List<int>>;
       _sseSubscription = stream
           .transform(utf8.decoder)