feat(wip): 경매 입찰 기능

hwe/sammo/DTO/AuctionBidItemData.php

@@ -2,11 +2,16 @@
 
 namespace sammo\DTO;
 
+use sammo\DTO\Attr\NullIsUndefined;
+
 class AuctionBidItemData extends DTO
 {
   public function __construct(
-    public string $ownerName,
+    #[NullIsUndefined]
+    public ?string $ownerName,
     public string $generalName,
+    #[NullIsUndefined]
+    public ?int $priority,
   ) {
   }
 }