chore: Nuxt 4 upgrade (#7426)

frontend/app/composables/use-navigation-warning.ts

@@ -0,0 +1,20 @@
+export function useNavigationWarning() {
+  return { activateNavigationWarning, deactivateNavigationWarning };
+}
+
+/**
+ * Displays a warning before the user navigates to another page
+ * e.g., by clicking a link (which isn't internal and rendered without page load),
+ * reloading the page,
+ * or closing the tab.
+ */
+const activateNavigationWarning = () => {
+  window.onbeforeunload = () => true;
+};
+
+/**
+ * Disables the warning when navigating to a page
+ */
+const deactivateNavigationWarning = () => {
+  window.onbeforeunload = null;
+};