Problem
What problem does this solve?
现在Qoder md文件预览还是需要侧边切换，使用极其不方便，开启后编辑器被分为四列（资源管理器、编辑器、预览、AI对话栏），无法正常查看md预览
Solution
How should it work?
新版VSC已经提供一键切换预览or编辑md的功能，还原生提供了mermaid的支持
Use Case
When would you use this?
查看md预览效果时
Priority
-
High - Blocking issue -
Medium - Important improvement -
Low - Nice to have
Additional Info
(Optional: screenshots, examples, links)