Want links to repo from recent agent sessions in empty workspace

[bamurtaugh]

Ref https://github.com/microsoft/vscode-internalbacklog/issues/6388

• Empty VS Code workspace, no folders or files
• Open chat sidebar
• ✅ See agent sessions from all my workspaces, which I'd expect in any empty workspace
  • 
• ✅ I can click on changed files and see the multi diff editor
• ❓ I can't fully interact with their resulting artifacts, even though I'm presented options to do so
  • See more from PR card doesn't do anything
    • 
  • The apply and checkout options don't do anything
    • 

It'd be nice to guide users to open that workspace and then interact with its artifacts if users press these buttons (or, we could just entirely hide these buttons if a user doesn't have the workspace open).

I also think it'd be nice to have some sort of visual indicator / broad link to which workspace these sessions apply to.

[bamurtaugh]

Similar issue, but that applies when I do have the actual correct repo or workspace open: #281362.

[bamurtaugh]

Observed again in testing today - I think in the near term in empty workspaces, it'd be great to hide the buttons or provide an error/warning message when clicking them (See more from PR card, apply changes, checkout PR) - otherwise it feels like the links are broken, as they just no-op. And in the longer term, we could consider if we could guide users to actually open the right repo.