Sign out cleared ipx's cookies and showed its password page, while
Cloudflare Access still vouched for the person: nothing was signed out,
and the page looked like the wrong login. /api/me now says, for someone
the proxy signed in, where to go instead ([web] sign_out_url, which is
/cdn-cgi/access/logout behind Access), and /login sends anyone the proxy
vouches for on to their feeds. The header check both use is one function.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TAC7sLVqfKmY6rsTLXzNgk