按用途整理文件并添加 README 和导航文档

[LUOYANGZHAOZIHANG]

整理项目结构：添加 monitoring/, performance-testing/, deployment/, security/ 并新增多份 README 与 FILE_STRUCTURE.md。提交：0e237e6、081c362。请审阅并合并。

[CLAassistant]

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