Add i18n localization to support entity

- Add translation keys to support.qna namespace:
  - support.qna.registrationDate: QnA item registration date label
  - support.qna.status: QnA item status label

- Localize ui/qna-item.tsx:
  - Replace hardcoded "등록일" with translation key
  - Replace hardcoded "상태" with translation key

- Other support files (notice-item.tsx, faq-item.tsx) already localized

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/locales/en.json

@@ -184,6 +184,8 @@
             "merchant": "Merchant",
             "all": "All",
             "inquiryButton": "Submit Inquiry",
+            "registrationDate": "Registered",
+            "status": "Status",
             "categories": {
                 "all": "All",
                 "choose": "Choose",