ci: QEMU 自动引导 + 一键复现;docs: 测试计数修正(148→实测)与 host 测试命令 - #13

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/