Todo list rendering in chat

Testing #253074
1) I created a planning mode that instructs to create a plan in the form of a todo list.

Last interaction: [9a184135.copilotmd.txt](https://github.com/user-attachments/files/21008554/9a184135.copilotmd.txt)

Rendering in the chat view:
<img width="899" alt="Image" src="https://github.com/user-attachments/assets/052e930d-e804-4190-9df0-fa76c2ed044e" />