架构审阅整改批:边界面加固(C2 纪元谓词/C5 评估 rc/C3 门契约单源/C6 tools 分层,伞 #191) - #197

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/