mutex: lock-order checker compares latches within one environment only - #268

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/upload-artifact@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Advisory tier: shared-runner numbers are not comparable to the committed baseline. The authoritative comparison runs via workflow_dispatch on dedicated hardware.