Backend Fixes and Integration

There are remaining tasks: Fix session token expiration (currently getting 'token expired' and 'permission denied' errors), properly validate agent connection so that servers only show real data (right now, new servers show random or dummy data), fix the server details page errors, and finish the free/paid plan logic via WHMCS. Also need final UI/API bug fixes. Overall, system is ~80% done, but these backend and integration issues are critical to make it fully functional