feat: migrate prosappco from Firebase to NestJS REST API (Fase 2)

- Replace all Firebase* repositories with Api* repositories using HTTP + SharedPreferences JWT
- Remove Firebase.initializeApp() and firebase_messaging background handler from main.dart
- Update DI (app_di.dart) to inject Api* repositories instead of Firebase* ones
- Replace all Timestamp/cloud_firestore usage with ISO 8601 String dates
- Stub PhoneVerificationService (Firebase phone OTP → backend OTP when implemented)
- Add ApiService singleton with JWT management in lib/services/
- Legacy firebase_*_repository.dart files preserved for Fase 4 cleanup

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/components/general_drawer.dart

@@ -1,4 +1,3 @@
-import 'package:firebase_auth/firebase_auth.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
@@ -233,9 +232,9 @@ class GeneralDrawer extends StatelessWidget {
                                           );
                                         },
                                         future: Injector.appInstance
-                                            .get<FirebaseServiceRepository>()
+                                            .get<ApiServiceRepository>()
                                             .countPendingServicesForProfessional(
-                                                FirebaseAuth.instance.currentUser!.uid),
+                                                ApiUserRepository.currentUserId ?? ''),
                                       )
                                     : const Icon(
                                         Icons.keyboard_arrow_right,
@@ -477,9 +476,9 @@ class GeneralDrawer extends StatelessWidget {
                       );
                     },
                     future: Injector.appInstance
-                        .get<FirebaseServiceRepository>()
+                        .get<ApiServiceRepository>()
                         .countPendingServicesForProfessional(
-                            FirebaseAuth.instance.currentUser!.uid),
+                            ApiUserRepository.currentUserId ?? ''),
                   ),
                 ),
               )

lib/components/general_reputation.dart

@@ -23,7 +23,7 @@ class _GeneralReputationState extends State<GeneralReputation> {
   void initState() {
     super.initState();
 
-    final repository = Injector.appInstance.get<FirebaseScoreRepository>();
+    final repository = Injector.appInstance.get<ApiScoreRepository>();
     reputation = repository.getReputationByUserId(widget.userId);
   }