fixed save button timestamp

frontend/src/pages/constructor.tsx

@@ -332,6 +332,18 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
     [activePageId, pages],
   );
 
+  // Last project-level save: most recent updatedAt across all pages
+  const lastProjectSaveAt = useMemo(() => {
+    if (!pages.length) return null;
+    return pages.reduce((latest, page) => {
+      if (!page.updatedAt) return latest;
+      if (!latest) return page.updatedAt;
+      return new Date(page.updatedAt) > new Date(latest)
+        ? page.updatedAt
+        : latest;
+    }, null as string | null);
+  }, [pages]);
+
   // Transition preview state management
   const {
     preview: transitionPreview,
@@ -1723,7 +1735,7 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
                   : '/projects/projects-list',
               )
             }
-            lastSavedAt={activePage?.updatedAt}
+            lastSavedAt={lastProjectSaveAt}
             lastSavedToStageAt={lastSavedToStage}
           />
         )}