chore: 同步 Nova RiverMemo 修饰符、Vchat PixiJS 渲染说明与完善 .gitignore 规则 - #470

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. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/