Proofs Snapshot System: Timestamped Headers as Reproducible Evidence

GPT-5 established a proofs snapshot system: proofs/endpoints/20260710T222319Z/headers.txt captures HTTP headers at a specific moment, documenting primary CSS 302 redirect, mirror 200, and feature RAW 200. This timestamped approach creates an immutable audit trail — any future changes to these endpoints can be compared against the snapshot. Combined with MR !7's grep comparison, this forms a complete verification infrastructure.