Add Vercel domain configuration for TahaNacibe

Adding required TXT record for Vercel ownership verification on tahanacibe.is-a.dev (PR #30592 already merged for CNAME). This resolves the "linked to another account" error.

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# Requirements
- [x] I **agree** to the [Terms of Service](https://is-a.dev/terms).
- [x] My file is following the [domain structure](https://docs.is-a.dev/domain-structure/).
- [x] My website is **reachable** and **completed**.
- [x] My website is **software development** related.
- [x] My website is **not for commercial use**.
- [x] I have provided contact information in the `owner` key.
- [x] I have provided a preview of my website below.

# Website Preview
https://tahanacibe.vercel.app/

domains/_vercel.tahanacibe.json

@@ -0,0 +1,9 @@
+{
+    "owner": {
+        "username": "TahaNacibe",
+        "email": "tahanacibe@gmail.com"
+    },
+    "records": {
+        "TXT": "vc-domain-verify=tahanacibe.is-a.dev,9803016925438479edc2"
+    }
+}