feat(#156): wizard admin création dossier AM (create/review).

Généralise ValidationAmWizard en AmDossierWizard ; le + Asmat ouvre
le mode création vers POST /assistantes-maternelles/dossier.

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

frontend/lib/widgets/admin/user_management_panel.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:p_tits_pas/screens/administrateurs/creation/gestionnaires_create.dart';
 import 'package:p_tits_pas/services/user_service.dart';
 import 'package:p_tits_pas/widgets/admin/admin_management_widget.dart';
+import 'package:p_tits_pas/widgets/admin/am_dossier_create_modal.dart';
 import 'package:p_tits_pas/widgets/admin/assistante_maternelle_management_widget.dart';
 import 'package:p_tits_pas/widgets/admin/common/admin_child_detail_modal.dart';
 import 'package:p_tits_pas/widgets/admin/dashboard_admin.dart';
@@ -28,6 +29,7 @@ class _UserManagementPanelState extends State<UserManagementPanel> {
   int _gestionnaireRefreshTick = 0;
   int _adminRefreshTick = 0;
   int _enfantRefreshTick = 0;
+  int _amRefreshTick = 0;
   final TextEditingController _searchController = TextEditingController();
   final TextEditingController _amCapacityController = TextEditingController();
   String? _parentStatus;
@@ -272,6 +274,7 @@ class _UserManagementPanelState extends State<UserManagementPanel> {
         );
       case 2:
         return AssistanteMaternelleManagementWidget(
+          key: ValueKey('ams-$_amRefreshTick'),
           searchQuery: _searchController.text,
           capacityMin: int.tryParse(_amCapacityController.text),
         );
@@ -331,6 +334,24 @@ class _UserManagementPanelState extends State<UserManagementPanel> {
       return;
     }
 
+    if (contentIndex == 2) {
+      await showDialog<void>(
+        context: context,
+        barrierDismissible: false,
+        builder: (dialogContext) {
+          return AmDossierCreateModal(
+            onClose: () => Navigator.of(dialogContext).pop(),
+            onSuccess: () {
+              Navigator.of(dialogContext).pop();
+              if (!mounted) return;
+              setState(() => _amRefreshTick++);
+            },
+          );
+        },
+      );
+      return;
+    }
+
     if (contentIndex == 3) {
       final created = await showDialog<bool>(
         context: context,
@@ -374,7 +395,7 @@ class _UserManagementPanelState extends State<UserManagementPanel> {
     ScaffoldMessenger.of(context).showSnackBar(
       const SnackBar(
         content: Text(
-          'La création parent / enfant / AM sera disponible avec le ticket #129.',
+          'La création parent sera disponible avec le ticket #129.',
         ),
       ),
     );