chore(infra): gate DB pool debug logs and de-duplicate rate-limit cleanup timer

.env.example

@@ -5,6 +5,8 @@
 # ============================================================================
 # PostgreSQL connection string
 DATABASE_URL="postgresql://user:password@localhost:5432/openframe?schema=public"
+# Enable PostgreSQL pool connect/acquire debug logs (set to "true" only when debugging)
+DB_POOL_DEBUG="false"
 
 # ============================================================================
 # AUTHENTICATION - NextAuth.js

lib/db.ts

@@ -10,6 +10,8 @@ const globalForPool = globalThis as unknown as {
   pgPool: Pool | undefined;
 };
 
+const isDbPoolDebugEnabled = process.env.DB_POOL_DEBUG === 'true';
+
 function createPool(connectionString: string): Pool {
   // Prevent multiple pools from being created during development (Next.js hot reload)
   if (globalForPool.pgPool) {
@@ -31,13 +33,15 @@ function createPool(connectionString: string): Pool {
     // Don't crash the app on unexpected pool errors
   });
 
-  pool.on('connect', () => {
-    console.debug('New database connection established');
-  });
+  if (isDbPoolDebugEnabled) {
+    pool.on('connect', () => {
+      console.debug('New database connection established');
+    });
 
-  pool.on('acquire', () => {
-    console.debug('Connection acquired from pool');
-  });
+    pool.on('acquire', () => {
+      console.debug('Connection acquired from pool');
+    });
+  }
 
   // Store pool globally to prevent multiple instances during development
   if (process.env.NODE_ENV !== 'production') {

lib/rate-limit.ts

@@ -1,6 +1,12 @@
 import { db } from '@/lib/db';
 import { NextResponse } from 'next/server';
 
+const RATE_LIMIT_CLEANUP_INTERVAL_MS = 5 * 60 * 1000;
+
+const globalForRateLimitCleanup = globalThis as unknown as {
+    rateLimitCleanupIntervalStarted?: boolean;
+};
+
 interface RateLimitConfig {
     windowMs: number;      // Time window in milliseconds
     maxRequests: number;   // Max requests per window
@@ -172,12 +178,15 @@ export async function cleanupRateLimits(): Promise<void> {
     }
 }
 
-// Start cleanup interval when the module is loaded (for self-hosted servers)
-// Cleanup runs every 5 minutes to remove expired rate limit entries
-if (typeof setInterval !== 'undefined') {
-    setInterval(() => {
+// Start cleanup interval once per process to avoid duplicate scheduling on module reload.
+if (!globalForRateLimitCleanup.rateLimitCleanupIntervalStarted && typeof setInterval !== 'undefined') {
+    const interval = setInterval(() => {
         cleanupRateLimits().catch(console.error);
-    }, 5 * 60 * 1000);
+    }, RATE_LIMIT_CLEANUP_INTERVAL_MS);
+
+    // Avoid keeping Node.js process alive because of housekeeping timers.
+    interval.unref?.();
+    globalForRateLimitCleanup.rateLimitCleanupIntervalStarted = true;
 }
 
 /**