ci(qa): L1 并发上限 + 它自己的 Docker 回归(把 #823/#835 真正带到 main —— 之前合错了 base) - #934

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/