fix: align Flutter endpoints and model parsing with actual NestJS backend

- Auth: phone login → POST /auth/phone (direct, no OTP); link phone → POST /auth/verify-phone; add email → POST /auth/link-email
- Services: replace query-param paths with dedicated role endpoints (/services/me, /services/professional/requests, /services/professional, etc.)
- Services: PATCH /services/:id → PATCH /services/:id/status
- Calendar: → GET /services/professional/calendar
- Professionals: /users/professionals → /professionals (handles {data:[...]} response)
- Professional info: /professional-info/:id → /professionals/:id; PATCH → /professionals/me
- Comments: /comments?... → /comments/user/:id and /comments/professional/:id
- Chat: /chats → /chat; start chat → POST /chat/start/:professionalId; poll GET /chat/:chatId/messages; send → POST /chat/:chatId/message
- Cities: /cities → GET /locations/countries (parse nested countries→regions→cities)
- Profesional.fromDocument: null-safe fields; convert schedules array→Schedules, specializations array→name/picture lists, payment_methods object/array
- Usuario.fromDocument: null-safe professional_state and id
- UsuarioProfesional.fromDocument: handle backend format (users nested, professional at top level)
- ScheduleEntity.parseTime: handle ISO8601 time strings from backend
- MessageEntity.fromDocument: accept sender_id (backend) or owner_id (legacy)

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

lib/providers/cities_provider.dart

@@ -20,17 +20,26 @@ class CitiesProvider extends ChangeNotifier {
 
   getCities() async {
     try {
-      final data = await _api.get('/cities') as List;
-      cities = data.map((e) {
-        final m = e as Map<String, dynamic>;
-        return City(
-          cityName: m['name'] as String,
-          coordsOfCity: m['coords'] as String? ?? '',
-          stateOfCity: m['state'] as String? ?? '',
-          countryOfCity: m['country'] as String? ?? 'Colombia',
-        );
-      }).toList();
-      cities.sort((a, b) => a.cityName.compareTo(b.cityName));
+      // GET /locations/countries returns nested {regions: [{cities: [...]}]}
+      final countries = await _api.get('/locations/countries') as List;
+      final result = <City>[];
+      for (final country in countries) {
+        final countryName = country['name'] as String? ?? 'Colombia';
+        for (final region in (country['regions'] as List? ?? [])) {
+          final regionName = region['name'] as String? ?? '';
+          for (final c in (region['cities'] as List? ?? [])) {
+            final lat = (c['latitude'] as num?)?.toDouble() ?? 0.0;
+            final lng = (c['longitude'] as num?)?.toDouble() ?? 0.0;
+            result.add(City(
+              cityName: c['name'] as String,
+              coordsOfCity: lat != 0.0 ? '$lat,$lng' : '',
+              stateOfCity: regionName,
+              countryOfCity: countryName,
+            ));
+          }
+        }
+      }
+      cities = result..sort((a, b) => a.cityName.compareTo(b.cityName));
     } catch (e) {
       print('Error obteniendo ciudades: $e');
     } finally {