fixes no git repo warning (#1863)

Fix broken git warning

<img width="797" height="482" alt="broken-screen"
src="https://github.com/user-attachments/assets/9c52ed9b-13d8-4f1d-bb37-7c51acac615d"
/>

codex-rs/tui/src/app.rs

@@ -233,7 +233,8 @@ impl App<'_> {
                                     widget.on_ctrl_c();
                                 }
                                 AppState::GitWarning { .. } => {
-                                    // No-op.
+                                    // Allow exiting the app with Ctrl+C from the warning screen.
+                                    self.app_event_tx.send(AppEvent::ExitRequest);
                                 }
                             }
                         }
@@ -415,7 +416,7 @@ impl App<'_> {
         let size = terminal.size()?;
         let desired_height = match &self.app_state {
             AppState::Chat { widget } => widget.desired_height(size.width),
-            AppState::GitWarning { .. } => 10,
+            AppState::GitWarning { .. } => size.height,
         };
 
         let mut area = terminal.viewport_area;