Pages serves index.html with 200 for unknown paths when there is no
404.html, so a never-published channel looked published and jq failed on
the HTML. Add a real 404 page and treat a 200 without a latest.json as
absent.
Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01JdMNbY5hLR7FjtfEE712xG
