fix(ci): inject CNAME conditionally; remove from static assets

docs/static/CNAME was copied unconditionally into every build, so fork
deployments claimed docs.mellea.ai as their custom domain. Remove the
file from static/ and inject it via peaceiris cname: input only on
upstream (generative-computing/mellea). Forks serving from their own
GitHub Pages URL are unaffected.

Assisted-by: Claude Code

Author: planetf1

.github/workflows/docs-publish.yml

@@ -266,6 +266,7 @@ jobs:
           publish_branch: gh-pages
           publish_dir: docs-site/
           force_orphan: true
+          cname: ${{ github.repository == 'generative-computing/mellea' && 'docs.mellea.ai' || '' }}
           user_name: "github-actions[bot]"
           user_email: "github-actions[bot]@users.noreply.github.com"
           commit_message: |