feat(File Tree): add file-tree shortcode support (#685)

* feat(File Tree): add `file-tree` shortcode support

* feat(file-tree): add ignoreList parameter to file-tree shortcode

* feat(file-tree): enhance file-tree shortcode with ignoreList and folderSlash options

* feat(file-tree): enhance file-tree shortcode to support data mode

* feat(file-tree): enhance file-tree shortcode to support file mode

* feat(file-tree): improve content parsing in file-tree shortcode

* feat(file-tree): improve root path validation and error handling in filesystem mode

* test(file-tree): add unit tests for `file-tree` shortcode

* feat(file-tree): add file-tree code block rendering support

* refactor(file-tree): extract filesystem scanning to get-file-tree partial

Move directory traversal and root path validation to a separate partial function,
consolidating all filesystem-related logic in one place. This simplifies the
shortcode implementation and ensures a unified data format for rendering.

* docs(readme): extend code fence and shortcode support for file tree in documentation

* feat(file-tree): add fullRootName parameter for root path display in file tree

* feat(file-tree): add language parameter to get-file-tree function

* feat(file-tree): add highlightList parameter for file-tree shortcode

* perf(file-tree): add level param for get-file-tree function to descend only level directories deep

README.zh-cn.md

@@ -147,6 +147,7 @@ pnpx fixit-cli create my-blog
 - 支持基于 [mermaid](https://github.com/knsv/mermaid) 的**图表** 代码块扩展语法和 shortcode
 - 支持基于 [ECharts](https://echarts.apache.org/) 的**交互式数据可视化** 代码块扩展语法和 shortcode
 - 支持 **Timeline** 的代码块扩展语法和 shortcode
+- 支持 **文件树** 的代码块扩展语法和 shortcode
 - 支持基于 [Mapbox GL JS](https://docs.mapbox.com/mapbox-gl-js) 的 **Mapbox** shortcode
 - 支持基于 [APlayer](https://github.com/MoePlayer/APlayer) 和 [MetingJS](https://github.com/metowolf/MetingJS) 的**音乐播放器** shortcode
 - 支持 **Bilibili 视频** 和 **抖音视频** shortcode