重构：文件系统模块化架构，增强 Markdown 渲染

- 拆分 FileSystem.vue 为模块化组件架构
- 新增 Markdown Mermaid 图表渲染支持
- 新增 180+ 编程语言代码高亮
- 修复编辑/预览模式切换渲染问题
- 优化亮色/暗色模式主题适配
- 新增 TypeScript 类型定义

web/package.json

@@ -29,7 +29,11 @@
     "@codemirror/state": "^6.5.3",
     "@codemirror/theme-one-dark": "^6.1.3",
     "@codemirror/view": "^6.39.8",
+    "@types/highlight.js": "^9.12.4",
+    "@types/mermaid": "^9.1.0",
+    "highlight.js": "^11.11.1",
     "marked": "^17.0.1",
+    "mermaid": "^11.12.2",
     "vue": "^3.5.26"
   },
   "devDependencies": {