The crawler/sitemap mechanics now live in the repo doc, not just in the
commit log: robots.txt is a build-time endpoint that must stay pure ASCII
(no charset on a text/plain response means non-ASCII renders as mojibake),
the policy is allow-all with enforcement deliberately left to Cloudflare,
why writing a real robots.txt demotes Cloudflare's placeholder from
replacement to prepend, and that lastmod/hreflang are derived so they must
never be hand-authored.