agent: Add component preview for Zed AI configuration (#33704)

As we are in the process of improving our Onboarding UX for Zed AI, I
added component previews for the Zed AI Configuration section. This
should make it easier to inspect the different states we can run into.

<img width="1198" alt="image"
src="https://github.com/user-attachments/assets/eb774f27-9091-450d-bfae-c688d533c25e"
/>


Release Notes:

- N/A

crates/language_model/src/language_model.rs

@@ -602,7 +602,7 @@ pub trait LanguageModelProvider: 'static {
 #[derive(PartialEq, Eq)]
 pub enum LanguageModelProviderTosView {
     /// When there are some past interactions in the Agent Panel.
-    ThreadtEmptyState,
+    ThreadEmptyState,
     /// When there are no past interactions in the Agent Panel.
     ThreadFreshStart,
     PromptEditorPopup,