fix(web): withOpacity à la place de withValues (Flutter 3.19 / dart2js)

Made-with: Cursor

frontend/lib/widgets/admin/validation_family_wizard.dart

@@ -309,7 +309,7 @@ class _ValidationFamilyWizardState extends State<ValidationFamilyWizard> {
 
   static List<BoxShadow> _enfantCardShadows() => [
         BoxShadow(
-          color: Colors.black.withValues(alpha: 0.06),
+          color: Colors.black.withOpacity(0.06),
           blurRadius: 14,
           offset: const Offset(0, 4),
         ),
@@ -514,10 +514,10 @@ class _ValidationFamilyWizardState extends State<ValidationFamilyWizard> {
       height: height,
       decoration: BoxDecoration(
         borderRadius: BorderRadius.circular(photoRadius),
-        border: Border.all(color: Colors.black.withValues(alpha: 0.08)),
+        border: Border.all(color: Colors.black.withOpacity(0.08)),
         boxShadow: [
           BoxShadow(
-            color: Colors.black.withValues(alpha: 0.05),
+            color: Colors.black.withOpacity(0.05),
             blurRadius: 6,
             offset: const Offset(0, 2),
           ),