Add TXT record for Google site verification

This PR updates domains/tayyib.json to add the Google Search Console verification TXT record for tayyib.is-a.dev.

The existing A record remains unchanged. This only adds the TXT record required for domain verification.

domains/tayyib.json

@@ -3,6 +3,7 @@
     "username": "tayyab1251"
   },
   "records": {
-    "A": ["152.67.10.6"]
+    "A": ["152.67.10.6"],
+    "TXT": "google-site-verification=mfAmEVdg1RKgSqGVu3VwBF9hoJg5yu5JHTxXeeqVUKg"
   }
 }