yasyf/Guides check

Verify every cc-guides artifact is fresh. Drift is non-blocking — a stale artifact emits a warning and the daily re-render heals it within 24h — while a broken setup (missing, dev, or local lock) still fails. The repo must carry a tracked .claude/fragments/cc-guides.lock; the action installs exactly the lock's cc-guides version (checksum-verified) and runs one check over every artifact, so a new cc-guides release can never redden it. Requires the repo to be checked out first (actions/checkout).