Add server status monitoring endpoint

- Add status.service.js with CPU, RAM, Disk, Backend stats
- RAM calculation matches htop (reads /proc/meminfo)
- Includes uploads folder size, DB table count
- Returns both system and backend (process) uptime

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/routes/admin.routes.js

@@ -50,4 +50,11 @@ router.delete(
   adminController.deleteUser
 );
 
+/**
+ * Server status
+ */
+
+// Server status (CPU, RAM, Disk, Network, Uptime)
+router.get('/server-status', adminController.getServerStatus);
+
 export default router;