feat(freestanding): 目标 C 库可覆盖、零 libc 档、分配器分层,以及七个生态包 - #466

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/