MSC4140: merge develop into the drop-state-interference branch - #3

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@v3, actions/setup-python@v4, peaceiris/actions-mdbook@ee69d230fe19748b7abf22df32acaa93833fad08. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/