Cut commentary from 104 to 24 lines across the new lint script, CI
config, and pre-push hook. Kept only: policy reference, why pattern is
loose, why scope is PR commits not history, and non-obvious CI behavior
notes. No logic lines changed.
Refs #4432
Three builder runs tonight carried a Co-Authored-By: Claude trailer
despite bold instructions forbidding it. A rule in a prompt is not a
control — this gate is. Flags commits in a PR's range carrying
co-authored-by + (claude OR anthropic OR noreply@anthropic.com),
case-insensitive, covering all observed spellings.
Wired into CI (new attribution-trailer job) and pre-push hook. Mirrors
existing lint scripts in structure and exit conventions. Pattern tested
against all three variants plus a normal commit.
