Set docs.agentpin.org custom domain, add CNAME to build

Author: jaschadub

.github/workflows/docs.yml

@@ -24,6 +24,7 @@ jobs:
           python-version: 3.x
       - run: pip install zensical
       - run: zensical build --clean
+      - run: echo 'docs.agentpin.org' > site/CNAME
       - uses: actions/upload-pages-artifact@v4
         with:
           path: site

zensical.toml

@@ -1,6 +1,6 @@
 [project]
 site_name = "AgentPin Documentation"
-site_url = "https://thirdkeyai.github.io/agentpin/"
+site_url = "https://docs.agentpin.org/"
 site_description = "Domain-anchored cryptographic identity protocol for AI agents"
 
 [project.repository]