fix(verify): demo-video のテストが実の $HOME に作業場所を作らないようにし、env-clean の誤った不合格を防ぐ - #3486

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/