The edge-purge integration was reverted in the previous commit; this
finishes the job. Public pages, the feed and /issues.json now say
`public, max-age=300` for browsers and shared caches alike, the code
comments and README explain why the longer s-maxage plus purge design
was dropped, and the rollout runbook loses its purge step, marks the
HTML cache rule optional, and warns to keep the record DNS-only until
the Universal SSL certificate is active.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Va5eMEmWEnjMXBsBob5FDW