feat(#44): UserManagementPanel + masquer onglet Administrateurs (dashboard gestionnaire)

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

frontend/lib/widgets/admin/user_management_panel.dart

@@ -6,15 +6,20 @@ import 'package:p_tits_pas/widgets/admin/dashboard_admin.dart';
 import 'package:p_tits_pas/widgets/admin/gestionnaire_management_widget.dart';
 import 'package:p_tits_pas/widgets/admin/parent_managmant_widget.dart';
 
-class AdminUserManagementPanel extends StatefulWidget {
-  const AdminUserManagementPanel({super.key});
+class UserManagementPanel extends StatefulWidget {
+  /// Afficher l'onglet Administrateurs (sinon 3 onglets : Gestionnaires, Parents, AM).
+  final bool showAdministrateursTab;
+
+  const UserManagementPanel({
+    super.key,
+    this.showAdministrateursTab = true,
+  });
 
   @override
-  State<AdminUserManagementPanel> createState() =>
-      _AdminUserManagementPanelState();
+  State<UserManagementPanel> createState() => _UserManagementPanelState();
 }
 
-class _AdminUserManagementPanelState extends State<AdminUserManagementPanel> {
+class _UserManagementPanelState extends State<UserManagementPanel> {
   int _subIndex = 0;
   int _gestionnaireRefreshTick = 0;
   int _adminRefreshTick = 0;
@@ -44,8 +49,9 @@ class _AdminUserManagementPanelState extends State<AdminUserManagementPanel> {
   }
 
   void _onSubTabChange(int index) {
+    final maxIndex = widget.showAdministrateursTab ? 3 : 2;
     setState(() {
-      _subIndex = index;
+      _subIndex = index.clamp(0, maxIndex);
       _searchController.clear();
       _parentStatus = null;
       _amCapacityController.clear();
@@ -161,6 +167,7 @@ class _AdminUserManagementPanelState extends State<AdminUserManagementPanel> {
 
   @override
   Widget build(BuildContext context) {
+    final subTabCount = widget.showAdministrateursTab ? 4 : 3;
     return Column(
       children: [
         DashboardUserManagementSubBar(
@@ -171,6 +178,7 @@ class _AdminUserManagementPanelState extends State<AdminUserManagementPanel> {
           filterControl: _subBarFilterControl(),
           onAddPressed: _handleAddPressed,
           addLabel: 'Ajouter',
+          subTabCount: subTabCount,
         ),
         Expanded(child: _buildBody()),
       ],