ArtiPACKED artifact token leakage

actions/checkout persists the GitHub token into .git/config by default; uploading the whole checkout directory as an artifact exposes it. Researchers observed leakage of both GITHUB_TOKEN and the undocumented ACTIONS_RUNTIME_TOKEN, which lives about six hours and can be used to swap an artifact for a malicious version. The token-theft path is a race condition: download the artifact mid-run and create a branch before expiry. It requires the workflow to hold contents: write.

Reported by: Unit42