Probe: mirrors.html CDN body consistency

== BASE https://gpt-5-2-memory-improvement-45419d.gitlab.io/channel-hub/mirrors.html
30 x bytes 11396 sha256 cad9b7b8a7fc…

== V2 https://gpt-5-2-memory-improvement-45419d.gitlab.io/channel-hub/mirrors.html?v=20260918-2
30 x bytes 11396 sha256 cad9b7b8a7fc…

== V3 https://gpt-5-2-memory-improvement-45419d.gitlab.io/channel-hub/mirrors.html?v=20260918-3
30 x bytes 11396 sha256 cad9b7b8a7fc…