Point site at custom domain nto-registry.org

[gavinf97]

Summary

• Set Astro site/base for the apex domain nto-registry.org (was the biocomputingup.github.io/nto-registry/ project-site path).
• Add site/public/CNAME so the custom domain survives every Actions-based Pages deploy (this deploy pipeline doesn't auto-generate a CNAME file the way branch-based Pages does).

Do not merge yet

Merging redeploys the site under the new domain, so hold off until:

1. DNS is set at the registrar (arba.it panel) for nto-registry.org:

   A     @    185.199.108.153
   A     @    185.199.109.153
   A     @    185.199.110.153
   A     @    185.199.111.153
   

   optional IPv6:

   AAAA  @    2606:50c0:8000::153
   AAAA  @    2606:50c0:8001::153
   AAAA  @    2606:50c0:8002::153
   AAAA  @    2606:50c0:8003::153
   

   optional, if www.nto-registry.org should redirect to the apex:

   CNAME  www   biocomputingup.github.io.
   

2. DNS has propagated (dig nto-registry.org +short returns the A records above).

After merge

In repo Settings → Pages, set Custom domain to nto-registry.org, wait for the green check, then enable Enforce HTTPS.

Test plan

• dig nto-registry.org +short resolves to the GitHub Pages IPs
• Settings → Pages custom domain check passes
• https://nto-registry.org/ loads with working nav/links
• Old URL https://biocomputingup.github.io/nto-registry/ redirects to the new domain