feat(#140): dashboard admin ch.6 — fiche parent, enfants, affiliation

Back: PATCH /parents/:id/fiche, attach/detach enfant, GET /enfants enrichi.
Front: modale parent éditable, onglet Enfants, fiche enfant, UserService.

Couvre doc 28 §6.1–6.2 ; tickets liés #115 #116 #130 #131 #137 #138.
Hors scope: fiche AM (#131), création admin (#129).

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

frontend/lib/models/parent_model.dart

@@ -1,18 +1,40 @@
+import 'package:p_tits_pas/models/parent_child_summary.dart';
 import 'package:p_tits_pas/models/user.dart';
 
 class ParentModel {
   final AppUser user;
   final int childrenCount;
+  final List<ParentChildSummary> children;
 
-  ParentModel({required this.user, this.childrenCount = 0});
+  ParentModel({
+    required this.user,
+    this.childrenCount = 0,
+    this.children = const [],
+  });
 
   factory ParentModel.fromJson(Map<String, dynamic> json) {
-    final userJson = json['user'] ?? json;
+    final userJson = Map<String, dynamic>.from(json['user'] ?? json);
+    if (json['numero_dossier'] != null && userJson['numero_dossier'] == null) {
+      userJson['numero_dossier'] = json['numero_dossier'];
+    }
     final user = AppUser.fromJson(userJson);
-    final children = json['parentChildren'] as List?;
+
+    final children = <ParentChildSummary>[];
+    final links = json['parentChildren'] as List?;
+    if (links != null) {
+      for (final link in links) {
+        if (link is Map<String, dynamic> && link['child'] is Map<String, dynamic>) {
+          children.add(
+            ParentChildSummary.fromJson(link['child'] as Map<String, dynamic>),
+          );
+        }
+      }
+    }
+
     return ParentModel(
       user: user,
-      childrenCount: children?.length ?? 0,
+      childrenCount: children.isNotEmpty ? children.length : (links?.length ?? 0),
+      children: children,
     );
   }
 }