docs: ops 索引去重（embedding 三平台单行）+ sdpa_math 补 MERGE.md - #18

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/