feat(#132): création enfant staff (onglet Enfants) — front + back.

Squash depuis develop : POST /enfants staff + parent_user_id, photo
multipart, modale création + sélection famille, fixes UX/birth_date.

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

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

@@ -1,14 +1,27 @@
+import 'dart:typed_data';
+
 import 'package:flutter/material.dart';
 import 'package:p_tits_pas/services/api/api_config.dart';
 import 'package:p_tits_pas/widgets/common/auth_network_image.dart';
 
-/// Cadre photo identité AM (35×45 mm) — même logique que [ValidationAmWizard].
+/// Cadre photo identité AM / enfant (35×45 mm) — même logique que [ValidationAmWizard].
 class AdminAmPhotoFrame extends StatelessWidget {
   final String? photoUrl;
+  final Uint8List? imageBytes;
+  final VoidCallback? onTap;
+  final VoidCallback? onClear;
+  final String emptyLabel;
 
   static const double idPhotoAspectRatio = 35 / 45;
 
-  const AdminAmPhotoFrame({super.key, this.photoUrl});
+  const AdminAmPhotoFrame({
+    super.key,
+    this.photoUrl,
+    this.imageBytes,
+    this.onTap,
+    this.onClear,
+    this.emptyLabel = 'Aucune photo',
+  });
 
   /// Largeur colonne photo pour remplir [height] (cadre inclus).
   static double columnWidthForHeight(double height) {
@@ -36,9 +49,12 @@ class AdminAmPhotoFrame extends StatelessWidget {
           ph = pw / ar;
         }
 
+        final hasLocal = imageBytes != null && imageBytes!.isNotEmpty;
+        final showClear = onClear != null && hasLocal;
+
         // Cadre gris = taille photo + padding uniforme ; centré dans la colonne
         // (évite le vide blanc en bas quand le conteneur parent est plus haut).
-        return Align(
+        Widget frame = Align(
           alignment: Alignment.topCenter,
           child: Container(
             decoration: BoxDecoration(
@@ -60,22 +76,81 @@ class AdminAmPhotoFrame extends StatelessWidget {
             ),
           ),
         );
+
+        if (onTap != null) {
+          frame = MouseRegion(
+            cursor: SystemMouseCursors.click,
+            child: GestureDetector(
+              onTap: onTap,
+              behavior: HitTestBehavior.opaque,
+              child: frame,
+            ),
+          );
+        }
+
+        if (!showClear) return frame;
+
+        return Stack(
+          clipBehavior: Clip.none,
+          children: [
+            frame,
+            Positioned(
+              top: 0,
+              right: 0,
+              child: Material(
+                color: Colors.transparent,
+                child: IconButton(
+                  tooltip: 'Retirer la photo',
+                  visualDensity: VisualDensity.compact,
+                  padding: EdgeInsets.zero,
+                  constraints: const BoxConstraints(
+                    minWidth: 32,
+                    minHeight: 32,
+                  ),
+                  icon: Icon(
+                    Icons.cancel,
+                    size: 22,
+                    color: Colors.grey.shade700,
+                  ),
+                  onPressed: onClear,
+                ),
+              ),
+            ),
+          ],
+        );
       },
     );
   }
 
   Widget _photoContent(String fullUrl, double pw, double ph) {
+    if (imageBytes != null && imageBytes!.isNotEmpty) {
+      return Image.memory(
+        imageBytes!,
+        width: pw,
+        height: ph,
+        fit: BoxFit.cover,
+        alignment: Alignment.topCenter,
+      );
+    }
     if (fullUrl.isEmpty) {
       return ColoredBox(
         color: Colors.grey.shade200,
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,
           children: [
-            Icon(Icons.person_off_outlined, size: 36, color: Colors.grey.shade400),
+            Icon(
+              onTap != null ? Icons.add_a_photo_outlined : Icons.person_off_outlined,
+              size: 36,
+              color: Colors.grey.shade400,
+            ),
             const SizedBox(height: 6),
-            Text(
-              'Aucune photo',
-              style: TextStyle(color: Colors.grey.shade600, fontSize: 11),
+            Padding(
+              padding: const EdgeInsets.symmetric(horizontal: 6),
+              child: Text(
+                emptyLabel,
+                textAlign: TextAlign.center,
+                style: TextStyle(color: Colors.grey.shade600, fontSize: 11),
+              ),
             ),
           ],
         ),
@@ -108,7 +183,11 @@ class AdminAmPhotoFrame extends StatelessWidget {
       },
       errorBuilder: (_, __, ___) => ColoredBox(
         color: Colors.grey.shade200,
-        child: Icon(Icons.broken_image_outlined, size: 36, color: Colors.grey.shade400),
+        child: Icon(
+          Icons.broken_image_outlined,
+          size: 36,
+          color: Colors.grey.shade400,
+        ),
       ),
     );
   }