agent: Add a setting choose the default view (#31353)

Related discussions #30240 #30596

Release Notes:

- Added an option on the settings file to choose either the `agent`
panel or the `thread` panel as the default assistant panel when you
first open it. On `settings.json`:
```json
{
  "agent": {
    "default_view": "thread", // default is agent
    }
}
```
8e5d50b85bAlvaro Parker committed on 5/26/2025, 2:33:18 PM· committed by GitHubparent625bf09
2 files changedLine totals unavailable