feat: Disable @radon by default

[latekvo]

@radon is a Chat Participant (CP). CPs don't allow for tool calling, can't traverse files, etc, etc. - they are very limited in scope compared to Agents. I assume it's very confusing for new users, that when you use @radon, all other tools stop working (#view_screenshot, #view_component_tree, etc.). It looks like something is broken on our side, while in reality this is simply how it works and there’s no workaround (VS Code docs, and the proposal to fix this in VS Code).

@radon CP was the very first implementation of Radon AI we've had. It used to be useful, but today it provides no edge over our agentic set of tools. All this, while it blocks the use of all all tools, whether that means reading a file, interacting with git, or checking logs - it's all blocked when the user decides to include @radon in their prompt. That’s why I think it’s safe to deprecate it. In my opinion, it causes more harm than good.

By "I assume it's very confusing for new users" and "causes more harm than good", i mean that I've had multiple people come up to me, asking why our AI tools aren't working, only to discover they were trying to do something like @radon What's on my screen?. The tipping point was this exact thing happening again - today.

To be discussed further.

How Has This Been Tested:

• Try using @radon in the copilot chat - it doesn't work (that's good).
  
• Go to settings, type: Radon AI: Enable Chat Participant
  
• Check the first option
  
• The @radon CP is now available in copilot chat.
  

How Has This Change Been Documented:

Documented in #1794

[filip131311]

thx 🎉