runtimec2: 功能完整性批1（string 10 项）+ 批2（struct·new / Ptr 修复） - #547

Process completed with exit code 1.

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/