docs: Phase J J6 public license and reuse guide -- Apache 2.0 terms, what you may/must/must-not do, artifact-specific constraints, dry-lab-only preservation requirement - #925

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/setup-python@v5. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/