Add missing notice category translation keys

Add comprehensive category translation keys for notice pages
to support all notice types used in the application.

Categories added:
- INTEREST_FREE_INSTALLMENT: Interest-Free Installment
- NEWS: News
- SERVICE_DISRUPTION_NOTICE: Service Disruption Notice
- MAINTENANCE_NOTICE: Maintenance Notice
- SERVICE_CHANGE_OR_ADDITION: Service Change or Addition
- IMPORTANT_NOTICE: Important Notice
- ADDITIONAL_SERVICE: Additional Service

Note: Notice pages (list-page.tsx and detail-page.tsx) are already
fully localized with useTranslation and t() function calls.

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

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

src/locales/en.json

@@ -166,11 +166,19 @@
             "title": "Notice",
             "searchPlaceholder": "Enter search keyword",
             "categories": {
+                "all": "All",
                 "ALL": "All",
                 "NOTICE": "Notice",
                 "EVENT": "Event",
                 "SERVICE": "Service",
-                "IMPORTANT": "Important"
+                "IMPORTANT": "Important",
+                "INTEREST_FREE_INSTALLMENT": "Interest-Free Installment",
+                "NEWS": "News",
+                "SERVICE_DISRUPTION_NOTICE": "Service Disruption Notice",
+                "MAINTENANCE_NOTICE": "Maintenance Notice",
+                "SERVICE_CHANGE_OR_ADDITION": "Service Change or Addition",
+                "IMPORTANT_NOTICE": "Important Notice",
+                "ADDITIONAL_SERVICE": "Additional Service"
             }
         },
         "faq": {