Agent-ready discovery

Leading words: skip unless, well-known discovery, policy match, HTTP contract, stack-agnostic, host-agnostic.

Publish the HTTP contract (URL, status, Content-Type, required fields). Serve it from origin, the static/public dir, or the edge in front of origin — whatever already ships the site. Do not prescribe a host product or a single framework.

Copy this file's phases into the todo list verbatim. Skipped steps stay with skip: / n/a:.

Phase 1 — Classify