Add database cleanup for stale data

- Add cleanupStaleData() function in db.ts
  - Deletes expired pending_verifications
  - Deletes unverified free-tier API keys
  - Deletes orphaned usage rows
  - Logs cleanup counts and returns results
- Add POST /v1/admin/cleanup endpoint (admin auth required)
- Run cleanup automatically 30s after startup (non-blocking)

src/index.ts

@@ -355,6 +355,16 @@ async function start() {
   logger.info(`Loaded ${getAllKeys().length} API keys`);
   const server = app.listen(PORT, () => logger.info(`DocFast API running on :${PORT}`));
 
+  // Run database cleanup 30 seconds after startup (non-blocking)
+  setTimeout(async () => {
+    try {
+      logger.info("Running scheduled database cleanup...");
+      await cleanupStaleData();
+    } catch (err) {
+      logger.error({ err }, "Startup cleanup failed (non-fatal)");
+    }
+  }, 30_000);
+
   let shuttingDown = false;
   const shutdown = async (signal: string) => {
     if (shuttingDown) return;

src/middleware/pdfRateLimit.ts

@@ -7,6 +7,13 @@ interface RateLimitEntry {
   resetTime: number;
 }
 
+interface RateLimitResult {
+  allowed: boolean;
+  limit: number;
+  remaining: number;
+  resetTime: number; // Unix timestamp in milliseconds
+}
+
 // Per-key rate limits (requests per minute)
 const FREE_RATE_LIMIT = 10;
 const PRO_RATE_LIMIT = 30;