feat(#131): en-tête fiche parent avec nom et co-parent.

Affiche le prénom/nom du parent en titre et le co-parent en sous-titre ; note handoff back dans archive/temporaires.

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

frontend/lib/widgets/admin/common/admin_parent_edit_modal.dart

@@ -3,6 +3,7 @@ import 'package:p_tits_pas/models/enfant_admin_model.dart';
 import 'package:p_tits_pas/utils/phone_utils.dart';
 import 'package:p_tits_pas/models/parent_child_summary.dart';
 import 'package:p_tits_pas/models/parent_model.dart';
+import 'package:p_tits_pas/models/user.dart';
 import 'package:p_tits_pas/services/user_service.dart';
 import 'package:p_tits_pas/widgets/admin/common/admin_child_detail_modal.dart';
 import 'package:p_tits_pas/widgets/admin/common/admin_enfant_user_card.dart';
@@ -36,6 +37,7 @@ class _AdminParentEditModalState extends State<AdminParentEditModal> {
 
   late String _statut;
   late List<ParentChildSummary> _children;
+  AppUser? _coParent;
   late final ScrollController _childrenScrollCtrl;
   bool _saving = false;
   bool _dirty = false;
@@ -62,6 +64,7 @@ class _AdminParentEditModalState extends State<AdminParentEditModal> {
     _villeCtrl = TextEditingController(text: u.ville ?? '');
     _cpCtrl = TextEditingController(text: u.codePostal ?? '');
     _statut = u.statut ?? 'en_attente';
+    _coParent = widget.parent.coParent;
     _children = List.of(widget.parent.children);
     _childrenScrollCtrl = ScrollController();
     for (final c in [
@@ -75,9 +78,15 @@ class _AdminParentEditModalState extends State<AdminParentEditModal> {
     ]) {
       c.addListener(_markDirty);
     }
+    _nomCtrl.addListener(_onNameFieldChanged);
+    _prenomCtrl.addListener(_onNameFieldChanged);
     _reloadChildren();
   }
 
+  void _onNameFieldChanged() {
+    setState(() {});
+  }
+
   @override
   void dispose() {
     for (final c in [
@@ -99,6 +108,22 @@ class _AdminParentEditModalState extends State<AdminParentEditModal> {
     if (!_dirty) setState(() => _dirty = true);
   }
 
+  String _headerTitle() {
+    final fn = _prenomCtrl.text.trim();
+    final ln = _nomCtrl.text.trim();
+    if (fn.isEmpty && ln.isEmpty) {
+      final fallback = widget.parent.user.fullName.trim();
+      return fallback.isNotEmpty ? fallback : 'Parent';
+    }
+    return '$fn $ln'.trim();
+  }
+
+  String? _coParentSubtitle() {
+    final name = _coParent?.fullName.trim() ?? '';
+    if (name.isEmpty) return null;
+    return 'Co-parent : $name';
+  }
+
   String _displayStatus(String status) {
     switch (status) {
       case 'actif':
@@ -202,7 +227,10 @@ class _AdminParentEditModalState extends State<AdminParentEditModal> {
       }).toList();
 
       if (!mounted) return;
-      setState(() => _children = kids);
+      setState(() {
+        _children = kids;
+        _coParent = refreshed.coParent;
+      });
     } catch (_) {}
   }
 
@@ -445,15 +473,35 @@ class _AdminParentEditModalState extends State<AdminParentEditModal> {
           mainAxisSize: MainAxisSize.min,
           children: [
             Row(
+              crossAxisAlignment: CrossAxisAlignment.start,
               children: [
-                const Padding(
-                  padding: EdgeInsets.fromLTRB(18, 16, 0, 10),
-                  child: Text(
-                    'Fiche parent',
-                    style: TextStyle(fontSize: 18, fontWeight: FontWeight.w700),
+                Expanded(
+                  child: Padding(
+                    padding: const EdgeInsets.fromLTRB(18, 16, 12, 10),
+                    child: Column(
+                      crossAxisAlignment: CrossAxisAlignment.start,
+                      children: [
+                        Text(
+                          _headerTitle(),
+                          style: const TextStyle(
+                            fontSize: 18,
+                            fontWeight: FontWeight.w700,
+                          ),
+                        ),
+                        if (_coParentSubtitle() != null) ...[
+                          const SizedBox(height: 4),
+                          Text(
+                            _coParentSubtitle()!,
+                            style: const TextStyle(
+                              fontSize: 13,
+                              color: Colors.black54,
+                            ),
+                          ),
+                        ],
+                      ],
+                    ),
                   ),
                 ),
-                const Spacer(),
                 SizedBox(width: 160, child: _statusDropdown()),
                 const SizedBox(width: 4),
                 IconButton(