R25 集成批 6 + R26 批 1：连接状态单一真相 + Seatbelt 沙箱 + 先劝再断 + 插件真 PG 门与 golden + MCP 设计稿 - #25

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, actions/setup-node@v4, pnpm/action-setup@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/