2026.11.8.1: mtest's test protocol in mcpp test, tests without main, one std module builder per entry, lock targets per plan, identity-key manifests - #906

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache/restore@v4, 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/