refactor(#93): extraire un widget UserList réutilisable

Centralise le pattern d'affichage des listes utilisateurs pour garantir une UI homogène entre gestionnaires, parents, assistantes maternelles et administrateurs.

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

frontend/lib/screens/administrateurs/admin_dashboardScreen.dart

@@ -1,10 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:p_tits_pas/services/configuration_service.dart';
-import 'package:p_tits_pas/widgets/admin/assistante_maternelle_management_widget.dart';
-import 'package:p_tits_pas/widgets/admin/gestionnaire_management_widget.dart';
-import 'package:p_tits_pas/widgets/admin/parent_managmant_widget.dart';
-import 'package:p_tits_pas/widgets/admin/admin_management_widget.dart';
 import 'package:p_tits_pas/widgets/admin/parametres_panel.dart';
+import 'package:p_tits_pas/widgets/admin/user_management_panel.dart';
 import 'package:p_tits_pas/widgets/app_footer.dart';
 import 'package:p_tits_pas/widgets/admin/dashboard_admin.dart';
 
@@ -18,7 +15,6 @@ class AdminDashboardScreen extends StatefulWidget {
 class _AdminDashboardScreenState extends State<AdminDashboardScreen> {
   bool? _setupCompleted;
   int mainTabIndex = 0;
-  int subIndex = 0;
   int settingsSubIndex = 0;
 
   @override
@@ -27,6 +23,11 @@ class _AdminDashboardScreenState extends State<AdminDashboardScreen> {
     _loadSetupStatus();
   }
 
+  @override
+  void dispose() {
+    super.dispose();
+  }
+
   Future<void> _loadSetupStatus() async {
     try {
       final completed = await ConfigurationService.getSetupStatus();
@@ -51,12 +52,6 @@ class _AdminDashboardScreenState extends State<AdminDashboardScreen> {
     });
   }
 
-  void onSubTabChange(int index) {
-    setState(() {
-      subIndex = index;
-    });
-  }
-
   void onSettingsSubTabChange(int index) {
     setState(() {
       settingsSubIndex = index;
@@ -89,10 +84,7 @@ class _AdminDashboardScreenState extends State<AdminDashboardScreen> {
       body: Column(
         children: [
           if (mainTabIndex == 0)
-            DashboardUserManagementSubBar(
-              selectedSubIndex: subIndex,
-              onSubTabChange: onSubTabChange,
-            )
+            const SizedBox.shrink()
           else
             DashboardSettingsSubBar(
               selectedSubIndex: settingsSubIndex,
@@ -114,17 +106,6 @@ class _AdminDashboardScreenState extends State<AdminDashboardScreen> {
         selectedSettingsTabIndex: settingsSubIndex,
       );
     }
-    switch (subIndex) {
-      case 0:
-        return const GestionnaireManagementWidget();
-      case 1:
-        return const ParentManagementWidget();
-      case 2:
-        return const AssistanteMaternelleManagementWidget();
-      case 3:
-        return const AdminManagementWidget();
-      default:
-        return const Center(child: Text('Page non trouvée'));
-    }
+    return const AdminUserManagementPanel();
   }
 }