feat: add database cleanup function and admin endpoint

- Add cleanupStaleData() in db.ts: purges expired verifications,
  unverified free-tier keys, and orphaned usage rows
- Add POST /admin/cleanup endpoint (admin auth required)
- Run cleanup 30s after startup (non-blocking)
- Fix missing import from broken previous commit

src/index.ts

@@ -23,7 +23,7 @@ import { pdfRateLimitMiddleware, getConcurrencyStats } from "./middleware/pdfRat
 import { initBrowser, closeBrowser } from "./services/browser.js";
 import { loadKeys, getAllKeys } from "./services/keys.js";
 import { verifyToken, loadVerifications } from "./services/verification.js";
-import { initDatabase, pool } from "./services/db.js";
+import { initDatabase, pool, cleanupStaleData } from "./services/db.js";
 import { swaggerSpec } from "./swagger.js";
 
 const app = express();
@@ -153,6 +153,17 @@ app.get("/v1/concurrency", authMiddleware, adminAuth, (_req: any, res: any) => {
   res.json(getConcurrencyStats());
 });
 
+// Admin: database cleanup (admin key required)
+app.post("/admin/cleanup", authMiddleware, adminAuth, async (_req: any, res: any) => {
+  try {
+    const results = await cleanupStaleData();
+    res.json({ status: "ok", cleaned: results });
+  } catch (err: any) {
+    logger.error({ err }, "Admin cleanup failed");
+    res.status(500).json({ error: "Cleanup failed", message: err.message });
+  }
+});
+
 // Email verification endpoint
 app.get("/verify", (req, res) => {
   const token = req.query.token as string;