Add Forgejo workflow to publish the API docs
zig build docs emits the autodoc bundle for the zsmtp module into
zig-out/docs, and the workflow publishes it to
https://jeff.ocj.page/zsmtp/ with git-pages-cli (now in the devshell)
on every push to main, mirroring the notmuch.zig setup.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012HBHFhoTYa8TU9GLwobfbx