feat(#93): optimiser l’affichage Parents/AM avec modale de détails

Intègre un bandeau unique (onglets à gauche, recherche/filtre en pilule, bouton Ajouter à droite) et compacte les cartes Parents/AM avec ouverture d’une modale complète sur Modifier (croix, actions Modifier/Supprimer).

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

frontend/lib/widgets/admin/admin_management_widget.dart

@@ -1,12 +1,16 @@
 import 'package:flutter/material.dart';
 import 'package:p_tits_pas/models/user.dart';
 import 'package:p_tits_pas/services/user_service.dart';
-import 'package:p_tits_pas/widgets/admin/common/admin_list_header.dart';
 import 'package:p_tits_pas/widgets/admin/common/admin_list_state.dart';
 import 'package:p_tits_pas/widgets/admin/common/admin_user_card.dart';
 
 class AdminManagementWidget extends StatefulWidget {
-  const AdminManagementWidget({super.key});
+  final String searchQuery;
+
+  const AdminManagementWidget({
+    super.key,
+    required this.searchQuery,
+  });
 
   @override
   State<AdminManagementWidget> createState() => _AdminManagementWidgetState();
@@ -16,21 +20,15 @@ class _AdminManagementWidgetState extends State<AdminManagementWidget> {
   bool _isLoading = false;
   String? _error;
   List<AppUser> _admins = [];
-  List<AppUser> _filteredAdmins = [];
-  final TextEditingController _searchController = TextEditingController();
 
   @override
   void initState() {
     super.initState();
     _loadAdmins();
-    _searchController.addListener(_onSearchChanged);
   }
 
   @override
-  void dispose() {
-    _searchController.dispose();
-    super.dispose();
-  }
+  void dispose() => super.dispose();
 
   Future<void> _loadAdmins() async {
     setState(() {
@@ -42,7 +40,6 @@ class _AdminManagementWidgetState extends State<AdminManagementWidget> {
       if (!mounted) return;
       setState(() {
         _admins = list;
-        _filteredAdmins = list;
         _isLoading = false;
       });
     } catch (e) {
@@ -54,42 +51,29 @@ class _AdminManagementWidgetState extends State<AdminManagementWidget> {
     }
   }
 
-  void _onSearchChanged() {
-    final query = _searchController.text.toLowerCase();
-    setState(() {
-      _filteredAdmins = _admins.where((u) {
-        final name = u.fullName.toLowerCase();
-        final email = u.email.toLowerCase();
-        return name.contains(query) || email.contains(query);
-      }).toList();
-    });
-  }
-
   @override
   Widget build(BuildContext context) {
+    final query = widget.searchQuery.toLowerCase();
+    final filteredAdmins = _admins.where((u) {
+      final name = u.fullName.toLowerCase();
+      final email = u.email.toLowerCase();
+      return name.contains(query) || email.contains(query);
+    }).toList();
+
     return Padding(
       padding: const EdgeInsets.all(16),
       child: Column(
         crossAxisAlignment: CrossAxisAlignment.stretch,
         children: [
-          AdminListHeader(
-            searchController: _searchController,
-            searchHint: 'Rechercher un administrateur...',
-            actionLabel: 'Créer un admin',
-            onActionPressed: () {
-              // TODO: Créer admin
-            },
-          ),
-          const SizedBox(height: 16),
           AdminListState(
             isLoading: _isLoading,
             error: _error,
-            isEmpty: _filteredAdmins.isEmpty,
+            isEmpty: filteredAdmins.isEmpty,
             emptyMessage: 'Aucun administrateur trouvé.',
             list: ListView.builder(
-              itemCount: _filteredAdmins.length,
+              itemCount: filteredAdmins.length,
               itemBuilder: (context, index) {
-                final user = _filteredAdmins[index];
+                final user = filteredAdmins[index];
                 return AdminUserCard(
                   title: user.fullName,
                   subtitleLines: [