Update interruption error message styling (#3470)

<img width="497" height="76" alt="image"
src="https://github.com/user-attachments/assets/a1ad279d-1d01-41cd-ac14-b3343a392563"
/>

<img width="493" height="74" alt="image"
src="https://github.com/user-attachments/assets/baf487ba-430e-40fe-8944-2071ec052962"
/>

codex-rs/tui/src/chatwidget.rs

@@ -289,7 +289,9 @@ impl ChatWidget {
     /// separated by newlines rather than auto‑submitting the next one.
     fn on_interrupted_turn(&mut self) {
         // Finalize, log a gentle prompt, and clear running state.
-        self.finalize_turn_with_error_message("Tell the model what to do differently".to_owned());
+        self.finalize_turn_with_error_message(
+            "Conversation interrupted - tell the model what to do differently".to_owned(),
+        );
 
         // If any messages were queued during the task, restore them into the composer.
         if !self.queued_user_messages.is_empty() {