feat: migrate Firebase → NestJS REST API backend

Replace all Firebase SDK (Auth, Firestore, Storage) with HTTP calls
to backend.prosapp.co/api/v1:

- New ApiService singleton (JWT token, GET/POST/PATCH/DELETE/upload)
- auth_provider: Firebase Auth → /auth/login, /auth/register, /auth/phone/*
- services_provider + calendar_services_provider → /services endpoints
- professional_provider + professionals_provider → /professional-info, /users/professionals
- profile_form_provider + professional_form_provider → /users/me, /storage/upload
- cities/professions/settings providers → /cities, /professions, /settings
- firebase_chat_repository → polling via /chats endpoints (3s interval)
- firebase_score_repository → polling via /comments endpoints (10s interval)
- professional_detail_provider → /users/:id + /professional-info/:id
- dashboard_view: Firestore.add → POST /services
- chat_view + rating_view: FirebaseAuth.uid → AuthProvider.user.id
- Models: Timestamp → String for createdAt fields
- google_fonts upgraded to ^8.1.0 (Dart 3.12 compat)
- Remove firebase_core, firebase_auth, cloud_firestore, firebase_storage from pubspec

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

lib/providers/calendar_services_provider.dart

@@ -1,16 +1,14 @@
 import 'package:flutter/material.dart';
-import 'package:cloud_firestore/cloud_firestore.dart';
 import 'package:prosapp_web_app/models/service.dart';
 import 'package:prosapp_web_app/models/servicio_profesional.dart';
 import 'package:prosapp_web_app/models/usuario.dart';
+import 'package:prosapp_web_app/services/api_service.dart';
 
 class CalendarServicesProvider extends ChangeNotifier {
   List<ServicioProfesional> services = [];
   ServicioProfesional? service;
   bool isLoading = true;
-
-  final _servicesCollection = FirebaseFirestore.instance.collection('services');
-  final _usersCollection = FirebaseFirestore.instance.collection('users');
+  final _api = ApiService.instance;
 
   void logout() {
     services = [];
@@ -22,47 +20,29 @@ class CalendarServicesProvider extends ChangeNotifier {
   getServicesForProfessional(String userId) async {
     try {
       isLoading = true;
+      final data = await _api.get('/services?professional_id=$userId&status=1,3') as List;
+      final servicios = data.map((e) {
+        final m = e as Map<String, dynamic>;
+        return Service.fromJson(m, m['id'] as String);
+      }).toList();
 
-      final queryServices = await _servicesCollection
-          .where('professional_id', isEqualTo: userId)
-          .where('status', whereIn: [1, 3]).get();
+      final ids = servicios.map((s) => s.userId).toSet().toList();
+      final users = await Future.wait(ids.map((id) async {
+        final u = await _api.get('/users/$id');
+        return Usuario.fromDocument(u as Map<String, dynamic>);
+      }));
+      final usersMap = {for (var u in users) u.id: u};
 
-      final servicios = queryServices.docs.map(Service.fromDocument).toList();
-
-      final userIds = servicios.map((service) => service.userId).toList();
-
-      final queryUsers = await _usersCollection
-          .where(FieldPath.documentId, whereIn: userIds)
-          .get();
-
-      final users =
-          queryUsers.docs.map((e) => Usuario.fromDocument(e.data())).toList();
-
-      final usersMap = {for (var doc in users) doc.id: doc};
-
-      final servicesMap = (servicios.map((service) {
-        final user = usersMap[service.userId];
-
-        return ServicioProfesional(
-          user: user!,
-          service: service,
-        );
-      }).toList());
-
-      services = servicesMap
+      services = servicios
+          .map((s) => ServicioProfesional(user: usersMap[s.userId]!, service: s))
+          .toList()
         ..sort((a, b) {
           final dateA = DateTime.parse(a.service.day);
           final dateB = DateTime.parse(b.service.day);
-          final range1A =
-              a.service.range1Hour1.hour * 60 + a.service.range1Hour1.minute;
-          final range1B =
-              b.service.range1Hour1.hour * 60 + b.service.range1Hour1.minute;
-
-          if (dateA.compareTo(dateB) != 0) {
-            return dateA.compareTo(dateB);
-          } else {
-            return range1A.compareTo(range1B);
-          }
+          if (dateA != dateB) return dateA.compareTo(dateB);
+          final tA = a.service.range1Hour1.hour * 60 + a.service.range1Hour1.minute;
+          final tB = b.service.range1Hour1.hour * 60 + b.service.range1Hour1.minute;
+          return tA.compareTo(tB);
         });
     } catch (e) {
       print('Error obteniendo servicios: $e');