refactor(#155): option C — widgets partagés sans préfixe Admin.

Déplace les composants Admin* du dashboard partagé vers
widgets/dashboard/ (ChildDetailModal, AmEditModal, UserCard, Select*, …).
Conserve AdminManagementWidget et screens/administrateurs. Rename mécanique,
aucun changement de comportement.

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

frontend/lib/widgets/admin/parent_dossier_wizard.dart

@@ -14,7 +14,7 @@ import 'package:p_tits_pas/utils/enfant_status_utils.dart';
 import 'package:p_tits_pas/utils/name_format_utils.dart';
 import 'package:p_tits_pas/utils/phone_utils.dart';
 import 'package:p_tits_pas/utils/postal_utils.dart';
-import 'package:p_tits_pas/widgets/admin/common/admin_am_photo_frame.dart';
+import 'package:p_tits_pas/widgets/dashboard/am_photo_frame.dart';
 import 'package:p_tits_pas/widgets/admin/common/validation_detail_section.dart';
 import 'package:p_tits_pas/widgets/admin/validation_modal_theme.dart';
 import 'package:p_tits_pas/widgets/admin/validation_refus_form.dart';
@@ -860,7 +860,7 @@ class _ParentDossierWizardState extends State<ParentDossierWizard> {
                                 child: SizedBox(
                                   width: pw,
                                   height: ph,
-                                  child: AdminAmPhotoFrame(
+                                  child: AmPhotoFrame(
                                     photoUrl: child.photoBytes == null
                                         ? child.existingPhotoUrl
                                         : null,