tui: improve rendering of search cell (#8273)

before:

<img width="795" height="150" alt="Screenshot 2025-12-18 at 10 48 01 AM"
src="https://github.com/user-attachments/assets/6f4d8856-b4c2-4e2a-b60a-b86f82b956a0"
/>

after:

<img width="795" height="150" alt="Screenshot 2025-12-18 at 10 48 39 AM"
src="https://github.com/user-attachments/assets/dd0d167a-5d09-4bb7-9d36-95a2eb1aaa83"
/>

codex-rs/tui2/src/chatwidget.rs

@@ -891,10 +891,7 @@ impl ChatWidget {
 
     fn on_web_search_end(&mut self, ev: WebSearchEndEvent) {
         self.flush_answer_stream_with_separator();
-        self.add_to_history(history_cell::new_web_search_call(format!(
-            "Searched: {}",
-            ev.query
-        )));
+        self.add_to_history(history_cell::new_web_search_call(ev.query));
     }
 
     fn on_get_history_entry_response(