feat(#44): dashboard gestionnaire + redirection login rôle gestionnaire

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

frontend/lib/screens/auth/login_screen.dart

@@ -131,9 +131,11 @@ class _LoginPageState extends State<LoginScreen> with WidgetsBindingObserver {
     switch (role.toLowerCase()) {
       case 'super_admin':
       case 'administrateur':
-      case 'gestionnaire':
         context.go('/admin-dashboard');
         break;
+      case 'gestionnaire':
+        context.go('/gestionnaire-dashboard');
+        break;
       case 'parent':
         context.go('/parent-dashboard');
         break;

frontend/lib/screens/gestionnaire/gestionnaire_dashboard_screen.dart

@@ -0,0 +1,45 @@
+import 'package:flutter/material.dart';
+import 'package:p_tits_pas/widgets/admin/dashboard_admin.dart';
+import 'package:p_tits_pas/widgets/admin/user_management_panel.dart';
+import 'package:p_tits_pas/widgets/app_footer.dart';
+
+/// Dashboard gestionnaire – même shell que l'admin, sans onglet Paramètres.
+/// Réutilise [AdminUserManagementPanel].
+class GestionnaireDashboardScreen extends StatefulWidget {
+  const GestionnaireDashboardScreen({super.key});
+
+  @override
+  State<GestionnaireDashboardScreen> createState() =>
+      _GestionnaireDashboardScreenState();
+}
+
+class _GestionnaireDashboardScreenState extends State<GestionnaireDashboardScreen> {
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: PreferredSize(
+        preferredSize: const Size.fromHeight(60.0),
+        child: Container(
+          decoration: BoxDecoration(
+            border: Border(
+              bottom: BorderSide(color: Colors.grey.shade300),
+            ),
+          ),
+          child: DashboardAppBarAdmin(
+            selectedIndex: 0,
+            onTabChange: (_) {},
+            showSettingsTab: false,
+            roleLabel: 'Gestionnaire',
+            setupCompleted: true,
+          ),
+        ),
+      ),
+      body: Column(
+        children: [
+          const Expanded(child: AdminUserManagementPanel()),
+          const AppFooter(),
+        ],
+      ),
+    );
+  }
+}