feat(admin): onglet À valider, dossier unifié et modales de validation

- Onglet « À valider » (AM + familles), pending-families et détail dossier par numéro.
- Wizards validation AM et famille, modale commune, chargement via GET /dossiers/:num.
- UI : cartes enfants, photo AM (cadre uniforme, ratio), NIR affiché formaté (espaces autour du tiret).
- Backend : DTO / routes parents pending ; scripts de test et mise à jour issue Gitea.

Tickets #107, #119.

Made-with: Cursor

frontend/lib/models/user.dart

@@ -15,6 +15,7 @@ class AppUser {
   final String? codePostal;
   final String? relaisId;
   final String? relaisNom;
+  final String? numeroDossier;
 
   AppUser({
     required this.id,
@@ -33,40 +34,50 @@ class AppUser {
     this.codePostal,
     this.relaisId,
     this.relaisNom,
+    this.numeroDossier,
   });
 
+  static String _str(dynamic v) {
+    if (v == null) return '';
+    if (v is String) return v;
+    return v.toString();
+  }
+
+  static DateTime _date(dynamic v) {
+    if (v == null) return DateTime.now();
+    if (v is DateTime) return v;
+    try {
+      return DateTime.parse(v.toString());
+    } catch (_) {
+      return DateTime.now();
+    }
+  }
+
   factory AppUser.fromJson(Map<String, dynamic> json) {
     final relaisJson = json['relais'];
     final relaisMap =
         relaisJson is Map<String, dynamic> ? relaisJson : <String, dynamic>{};
 
     return AppUser(
-      id: (json['id'] as String?) ?? '',
-      email: (json['email'] as String?) ?? '',
-      role: (json['role'] as String?) ?? '',
-      createdAt: json['cree_le'] != null
-          ? DateTime.parse(json['cree_le'] as String)
-          : (json['createdAt'] != null
-              ? DateTime.parse(json['createdAt'] as String)
-              : DateTime.now()),
-      updatedAt: json['modifie_le'] != null
-          ? DateTime.parse(json['modifie_le'] as String)
-          : (json['updatedAt'] != null
-              ? DateTime.parse(json['updatedAt'] as String)
-              : DateTime.now()),
+      id: _str(json['id']),
+      email: _str(json['email']),
+      role: _str(json['role']),
+      createdAt: _date(json['cree_le'] ?? json['createdAt']),
+      updatedAt: _date(json['modifie_le'] ?? json['updatedAt']),
       changementMdpObligatoire:
-          json['changement_mdp_obligatoire'] as bool? ?? false,
-      nom: json['nom'] as String?,
-      prenom: json['prenom'] as String?,
-      statut: json['statut'] as String?,
-      telephone: json['telephone'] as String?,
-      photoUrl: json['photo_url'] as String?,
-      adresse: json['adresse'] as String?,
-      ville: json['ville'] as String?,
-      codePostal: json['code_postal'] as String?,
+          json['changement_mdp_obligatoire'] == true,
+      nom: json['nom'] is String ? json['nom'] as String : null,
+      prenom: json['prenom'] is String ? json['prenom'] as String : null,
+      statut: json['statut'] is String ? json['statut'] as String : null,
+      telephone: json['telephone'] is String ? json['telephone'] as String : null,
+      photoUrl: json['photo_url'] is String ? json['photo_url'] as String : null,
+      adresse: json['adresse'] is String ? json['adresse'] as String : null,
+      ville: json['ville'] is String ? json['ville'] as String : null,
+      codePostal: json['code_postal'] is String ? json['code_postal'] as String : null,
       relaisId: (json['relaisId'] ?? json['relais_id'] ?? relaisMap['id'])
           ?.toString(),
       relaisNom: relaisMap['nom']?.toString(),
+      numeroDossier: json['numero_dossier'] is String ? json['numero_dossier'] as String : null,
     );
   }
 
@@ -88,6 +99,7 @@ class AppUser {
       'code_postal': codePostal,
       'relais_id': relaisId,
       'relais_nom': relaisNom,
+      'numero_dossier': numeroDossier,
     };
   }