feat: xlings 作为运行时底座 —— subos 环境到达程序 + self-contained 的 /proc/self/exe 陷阱 (#352, #375) (2026.8.8.1) - #376

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