feat(dashboard-admin): connect admin dashboard to real API data (Ticket #92)

- Frontend:
  - Create UserService to handle user-related API calls (gestionnaires, parents, AMs, admins)
  - Update AdminDashboardScreen to use dynamic widgets
  - Implement dynamic management widgets:
    - GestionnaireManagementWidget
    - ParentManagementWidget
    - AssistanteMaternelleManagementWidget
    - AdminManagementWidget
  - Add data models: ParentModel, AssistanteMaternelleModel
  - Update AppUser model
  - Update ApiConfig

- Backend:
  - Update controllers (Parents, AMs, Gestionnaires, Users) to allow ADMINISTRATEUR role to list users
  - Note: Gestionnaires endpoint is currently bypassed in frontend (using /users filter) due to module import issue (documented in docs/92_NOTE-BACKEND-GESTIONNAIRES.md)

- Docs:
  - Add note about backend fix for Gestionnaires module
  - Update .cursorrules to forbid worktrees

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/lib/services/api/api_config.dart

@@ -15,6 +15,9 @@ class ApiConfig {
   static const String users = '/users';
   static const String userProfile = '/users/profile';
   static const String userChildren = '/users/children';
+  static const String gestionnaires = '/gestionnaires';
+  static const String parents = '/parents';
+  static const String assistantesMaternelles = '/assistantes-maternelles';
 
   // Configuration (admin)
   static const String configuration = '/configuration';