feat(Validators): add server ID validation function to prevent path traversal and unsafe characters; update routes to utilize new validation logic

backend/routes/mikrotikBackupRoutes.js

@@ -298,7 +298,7 @@ async function runBackupNow(req, res) {
       comment: 'Manual backup from UI (/api/mikrotik/backups/run)',
     });
 
-    return sendOk(res, {
+    return res.json({
       ok: true,
       key,
       serverId,