docs(viewer): finalize Director 5.21.7 release provenance

[Shuang-su]

产品PR #131已常规合并为f7459408edecc7ef0b744dd9c5aaa3620a4ebd51。本PR只将未生产发布的5.21.7来源记录指向实际产品SHA，同步公开镜像和索引release字段，并追加完整验证；原源码由不可变viewer-v5.21.7-rc1保留，旧正式版本记录与所有资源内容不变。

• Viewer144/144、MCL、release-contract和126份文档链接通过。产品精确HEAD CI 37884934299成功；本PR精确HEAD d30e2700687c9c661a062ad61b778cdfca3852ef 的 CI 37885618856所选Viewer/Director、数据、文档、治理及summary成功，其他组件未选中。
• 四场景100轮960×540程序化连续输入均有新画面、最终状态和128收敛；原生控件证据另列。四场景十次重复、三档真实4K、四转场取消重试及24本地/24来源状态见验证记录。
• GitHub原生7图2视频已在MF-106/MF-62正文，匿名GET字节一致；完整站点预览8文件/300路由、8redirect/9header及真实资源摄影已验证。

合并后正式tag和build使用实际本PR合并SHA，生产仍待ready候选回读、提升、实际UI输出和15分钟观察。回退5.21.6部署6ac7ec0fa8239794c0ab5d12。没有用上述数值一致宣称修复源扫描缺失或全部材料光学。

Refs: MF-106, MF-62

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[chatgpt-codex-connector]

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-09T04:57:43.511263Z	d30e270	PR opened

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