feat: Bandeau générique, dashboards et doc (squash develop, Closes #100)

- Bandeau générique (DashboardBandeau) pour Parent, Admin, Gestionnaire, AM
- ParentDashboardScreen, AdminDashboardScreen, GestionnaireDashboardScreen, AM dashboard
- AppFooter responsive, scripts Gitea (create/list issues parent API)
- Doc: ticket #101 Inscription Parent API, mise à jour 23_LISTE-TICKETS
- User.fromJson robustesse (nullable id/email/role)
- Suppression dashboard_app_bar.dart au profit de dashboard_bandeau.dart

Refs: #100, #101
Made-with: Cursor

frontend/lib/config/app_router.dart

@@ -22,6 +22,9 @@ import '../screens/home/home_screen.dart';
 import '../screens/administrateurs/admin_dashboardScreen.dart';
 import '../screens/gestionnaire/gestionnaire_dashboard_screen.dart';
 import '../screens/home/parent_screen/ParentDashboardScreen.dart';
+import '../screens/am/am_dashboard_screen.dart';
+import '../screens/legal/privacy_page.dart';
+import '../screens/legal/legal_page.dart';
 import '../screens/unknown_screen.dart';
 
 // --- Provider Instances ---
@@ -64,7 +67,16 @@ class AppRouter {
       ),
       GoRoute(
         path: '/am-dashboard',
-        builder: (BuildContext context, GoRouterState state) => const HomeScreen(),
+        builder: (BuildContext context, GoRouterState state) =>
+            const AmDashboardScreen(),
+      ),
+      GoRoute(
+        path: '/privacy',
+        builder: (BuildContext context, GoRouterState state) => const PrivacyPage(),
+      ),
+      GoRoute(
+        path: '/legal',
+        builder: (BuildContext context, GoRouterState state) => const LegalPage(),
       ),
 
       // --- Parent Registration Flow ---