fix: [bending] 품목 resolveItem eager loading 컬럼 수정

- item 관계 로드 시 specification → attributes로 변경

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/Services/BendingCodeService.php

@@ -136,7 +136,7 @@ public function resolveItem(string $prodCode, string $specCode, string $lengthCo
             ->where('spec_code', $specCode)
             ->where('length_code', $lengthCode)
             ->where('is_active', true)
-            ->with('item:id,code,name,specification,unit')
+            ->with('item:id,code,name,attributes,unit')
             ->first();
 
         if (! $mapping || ! $mapping->item) {