The guard (#5119, PR #5120 on v2/main) runs on pull_request_target, which
loads the workflow and script from main. Bring the same three files here
byte-for-byte, so the check can run on, and be required for, PRs into main
before the next milestone merge carries them.
Part of #5119
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: cliffhall <cliff@futurescale.com>