feat(queue): implement form-expiry-check maintenance job

Marks pending form_submissions whose expires_at has passed
as 'expired'. Logs the count of rows transitioned each run.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/queue/workers/maintenance.ts

@@ -1,6 +1,9 @@
 import { Worker, type Job } from 'bullmq';
+import { and, eq, lt } from 'drizzle-orm';
 
 import type { ConnectionOptions } from 'bullmq';
+import { db } from '@/lib/db';
+import { formSubmissions } from '@/lib/db/schema/documents';
 import { logger } from '@/lib/logger';
 import { QUEUE_CONFIGS } from '@/lib/queue';
 
@@ -15,8 +18,14 @@ export const maintenanceWorker = new Worker(
         break;
       }
       case 'form-expiry-check': {
-        // TODO(L3): mark expired form submissions
-        logger.info('Form expiry check — not yet implemented');
+        const result = await db
+          .update(formSubmissions)
+          .set({ status: 'expired' })
+          .where(
+            and(eq(formSubmissions.status, 'pending'), lt(formSubmissions.expiresAt, new Date())),
+          )
+          .returning({ id: formSubmissions.id });
+        logger.info({ expired: result.length }, 'Form expiry check complete');
         break;
       }
       default: