chore: remove debug endpoints and update configuration

- Removed debug-packages and test-sync API endpoints no longer needed
- Extracted sync status management into shared lib/sync/status module
- Updated Next.js config to remove deprecated experimental appDir flag
- Added port specification to production start script for consistency

package.json

@@ -5,7 +5,7 @@
   "scripts": {
     "dev": "next dev -p 3002",
     "build": "next build",
-    "start": "next start",
+    "start": "next start -p 3002",
     "lint": "next lint",
     "type-check": "tsc --noEmit",
     "test:db": "node scripts/test-db.js",