郵送依頼画面の表示条件を修正

src/pages/app/MailOrder.tsx

@@ -88,6 +88,10 @@ export default function MailOrder() {
     },
   });
 
+  const canMailOrder = useMemo(() => {
+    return !!order && order.status_order_mail_datetime === null;
+  }, [order]);
+
   const currentStep = useMemo(() => {
     if (mode === "input") return 0;
     if (mode === "confirm") return 1;
@@ -107,6 +111,10 @@ export default function MailOrder() {
     return null;
   }
 
+  if (!canMailOrder) {
+    return null;
+  }
+
   return (
     <>
       <Box sx={{ p: 3, pt: 5, mx: "auto", maxWidth: 500 }} textAlign="center">