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/widgets/admin/relais_management_panel.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:p_tits_pas/models/relais_model.dart';
+import 'package:p_tits_pas/utils/phone_utils.dart';
 import 'package:p_tits_pas/services/relais_service.dart';
 
 class RelaisManagementPanel extends StatefulWidget {
@@ -723,7 +724,7 @@ class _RelaisFormDialogState extends State<_RelaisFormDialog> {
           inputFormatters: [
             FilteringTextInputFormatter.digitsOnly,
             LengthLimitingTextInputFormatter(10),
-            _FrenchPhoneNumberFormatter(),
+            FrenchPhoneNumberFormatter(),
           ],
           decoration: const InputDecoration(
             labelText: 'Ligne fixe',
@@ -991,30 +992,6 @@ class _RelaisFormDialogState extends State<_RelaisFormDialog> {
   }
 }
 
-class _FrenchPhoneNumberFormatter extends TextInputFormatter {
-  @override
-  TextEditingValue formatEditUpdate(
-    TextEditingValue oldValue,
-    TextEditingValue newValue,
-  ) {
-    final digits = newValue.text.replaceAll(RegExp(r'\D'), '');
-    final buffer = StringBuffer();
-
-    for (var i = 0; i < digits.length; i++) {
-      if (i > 0 && i.isEven) {
-        buffer.write(' ');
-      }
-      buffer.write(digits[i]);
-    }
-
-    final formatted = buffer.toString();
-    return TextEditingValue(
-      text: formatted,
-      selection: TextSelection.collapsed(offset: formatted.length),
-    );
-  }
-}
-
 class _RelaisAddressFields extends StatelessWidget {
   final TextEditingController streetController;
   final TextEditingController postalCodeController;