fix(engine): loop-ring retention across forced windows + observer-negative rulings (combo-fb phases 0-2, chain 1) - #6838

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. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/