feat: 64 分片 uint64_t 位掩码、O(1) 热点 box 缓存与 SWAR 快路径 - #13

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/