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/models/usuario.dart

@@ -45,7 +45,7 @@ class Usuario {
 
   static Usuario fromDocument(Map<String, dynamic> doc) {
     return Usuario(
-      id: doc['id'],
+      id: (doc['id'] as String?) ?? '',
       email: doc['email'],
       phone: doc['phone'],
       name: doc['name'] ?? '',
@@ -54,7 +54,7 @@ class Usuario {
       picture: doc['picture'],
       birthday: doc['birthday'],
       gender: doc['gender'],
-      proState: intToEnum(doc['professional_state'] as int),
+      proState: intToEnum((doc['professional_state'] as int?) ?? 0),
       token: doc['token'],
     );
   }