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/am_dossier_wizard.dart

@@ -14,8 +14,8 @@ import 'package:p_tits_pas/utils/name_format_utils.dart';
 import 'package:p_tits_pas/utils/nir_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/admin/common/admin_detail_modal.dart';
+import 'package:p_tits_pas/widgets/dashboard/am_photo_frame.dart';
+import 'package:p_tits_pas/widgets/dashboard/detail_modal.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';
@@ -221,32 +221,32 @@ class _AmDossierWizardState extends State<AmDossierWizard> {
 
   void _emitStep() => widget.onStepChanged?.call(_step, _stepCount);
 
-  List<AdminDetailField> _photoProFields(DossierAM d) {
+  List<DetailField> _photoProFields(DossierAM d) {
     final u = d.user;
     return [
-      AdminDetailField(label: 'NIR', value: _formatNirForDisplay(d.nir)),
-      AdminDetailField(
+      DetailField(label: 'NIR', value: _formatNirForDisplay(d.nir)),
+      DetailField(
         label: 'Date de naissance',
         value: formatIsoDateFr(u.dateNaissance),
       ),
-      AdminDetailField(
+      DetailField(
         label: 'Ville de naissance',
         value: _v(u.lieuNaissanceVille),
       ),
-      AdminDetailField(
+      DetailField(
         label: 'Pays de naissance',
         value: _v(u.lieuNaissancePays),
       ),
-      AdminDetailField(label: 'N° Agrément', value: _v(d.numeroAgrement)),
-      AdminDetailField(
+      DetailField(label: 'N° Agrément', value: _v(d.numeroAgrement)),
+      DetailField(
         label: 'Date d’agrément',
         value: formatIsoDateFr(d.dateAgrement),
       ),
-      AdminDetailField(
+      DetailField(
         label: 'Capacité max (enfants)',
         value: d.nbMaxEnfants != null ? d.nbMaxEnfants.toString() : '–',
       ),
-      AdminDetailField(
+      DetailField(
         label: 'Places disponibles',
         value: d.placesDisponibles != null
             ? d.placesDisponibles.toString()
@@ -741,14 +741,14 @@ class _AmDossierWizardState extends State<AmDossierWizard> {
 
   Widget _buildStep1() {
     // Modale calée sur les TF ; photo étirée sur toute la hauteur utile
-    // (largeur = [AdminAmPhotoFrame.columnWidthForHeight], cadre inclus).
+    // (largeur = [AmPhotoFrame.columnWidthForHeight], cadre inclus).
     return LayoutBuilder(
       builder: (context, c) {
         final maxRowW = c.maxWidth;
         final maxRowH = c.maxHeight.clamp(0.0, double.infinity);
         final maxPhotoW = (maxRowW - _photoProGap - _proColumnMinWidth)
             .clamp(0.0, double.infinity);
-        var photoW = AdminAmPhotoFrame.columnWidthForHeight(maxRowH)
+        var photoW = AmPhotoFrame.columnWidthForHeight(maxRowH)
             .clamp(_photoColumnMinWidth, 360.0);
         if (photoW > maxPhotoW) photoW = maxPhotoW;
 
@@ -762,7 +762,7 @@ class _AmDossierWizardState extends State<AmDossierWizard> {
 
         final Widget photo;
         if (_isCreate) {
-          photo = AdminAmPhotoFrame(
+          photo = AmPhotoFrame(
             imageBytes: _photoBytes,
             onTap: _pickPhoto,
             onClear: _photoBytes != null ? _clearPhoto : null,