feat: add cleanup for unbound addresses feature (#739)

- Add unboundAddress cleanup type to backend cleanup logic
- Update CleanupSettings model with unbound address fields
- Add scheduled task for automatic unbound address cleanup
- Add UI controls in admin Maintenance panel for manual cleanup
- Add i18n support (en/zh) for unbound address cleanup labels
- Clean addresses not bound to any user created before n days

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

Co-authored-by: Claude <noreply@anthropic.com>

worker/src/common.ts

@@ -251,6 +251,12 @@ export const cleanup = async (
                 `created_at < datetime('now', '-${cleanDays} day')`
             )
             break;
+        case "unboundAddress":
+            await batchDeleteAddressWithData(
+                c,
+                `id NOT IN (SELECT address_id FROM users_address) AND created_at < datetime('now', '-${cleanDays} day')`
+            )
+            break;
         case "mails":
             await c.env.DB.prepare(`
                 DELETE FROM raw_mails WHERE created_at < datetime('now', '-${cleanDays} day')`