feat(#140): liste enfants unifiée — cartes, âge précis et cadre scrollable

Partage AdminEnfantUserCard entre fiche parent et onglet Enfants, enrichit ParentChildSummary (photo, dates) et compacte la modale parent.

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

frontend/lib/models/parent_child_summary.dart

@@ -1,15 +1,23 @@
+import 'package:p_tits_pas/models/enfant_admin_model.dart';
+
 /// Résumé enfant affiché dans la fiche parent (dashboard admin).
 class ParentChildSummary {
   final String id;
   final String? firstName;
   final String? lastName;
   final String status;
+  final String? photoUrl;
+  final String? birthDate;
+  final String? dueDate;
 
   ParentChildSummary({
     required this.id,
     this.firstName,
     this.lastName,
     required this.status,
+    this.photoUrl,
+    this.birthDate,
+    this.dueDate,
   });
 
   String get fullName {
@@ -26,9 +34,30 @@ class ParentChildSummary {
       firstName: (json['first_name'] ?? json['prenom'])?.toString(),
       lastName: (json['last_name'] ?? json['nom'])?.toString(),
       status: (json['status'] ?? json['statut'] ?? '').toString(),
+      photoUrl: json['photo_url']?.toString(),
+      birthDate: _dateString(json['birth_date']),
+      dueDate: _dateString(json['due_date']),
     );
   }
 
+  factory ParentChildSummary.fromEnfant(EnfantAdminModel enfant) {
+    return ParentChildSummary(
+      id: enfant.id,
+      firstName: enfant.firstName,
+      lastName: enfant.lastName,
+      status: enfant.status,
+      photoUrl: enfant.photoUrl,
+      birthDate: enfant.birthDate,
+      dueDate: enfant.dueDate,
+    );
+  }
+
+  static String? _dateString(dynamic v) {
+    if (v == null) return null;
+    if (v is String) return v.split('T').first;
+    return v.toString().split('T').first;
+  }
+
   /// Parse un lien `parentChildren` (objet enfant imbriqué ou id seul).
   static ParentChildSummary? fromParentChildLink(Map<String, dynamic> link) {
     final childRaw = link['child'] ?? link['enfant'];