Warn on tab close when create-flow module or wizard edits have not been saved.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/utils/test-utils.tsx

@@ -25,5 +25,12 @@ export function renderWithProviders(
   return render(ui, { wrapper: Wrapper, ...options });
 }
 
+/** True when a `beforeunload` listener called `preventDefault` (tab-close guard). */
+export function dispatchBeforeUnload(): boolean {
+  const event = new Event("beforeunload", { cancelable: true });
+  window.dispatchEvent(event);
+  return event.defaultPrevented;
+}
+
 // Re-export everything from @testing-library/react for convenience
 export * from "@testing-library/react";