assistant2: Show token count in the Prompt Editor view (#25091)

Release Notes:

- N/A

---------

Co-authored-by: Agus Zubiaga <hi@aguz.me>

crates/assistant_context_editor/src/context.rs

@@ -1190,11 +1190,14 @@ impl AssistantContext {
         let Some(model) = LanguageModelRegistry::read_global(cx).active_model() else {
             return;
         };
+        let debounce = self.token_count.is_some();
         self.pending_token_count = cx.spawn(|this, mut cx| {
             async move {
-                cx.background_executor()
-                    .timer(Duration::from_millis(200))
-                    .await;
+                if debounce {
+                    cx.background_executor()
+                        .timer(Duration::from_millis(200))
+                        .await;
+                }
 
                 let token_count = cx.update(|cx| model.count_tokens(request, cx))?.await?;
                 this.update(&mut cx, |this, cx| {