added timestamp to bloc cache, showing age in offline mode

lib/view/pages/overhang.dart

@@ -72,10 +72,6 @@ class Overhang extends StatelessWidget {
             trailing: const Icon(Icons.arrow_right),
             onTap: () => pushScreen(context, withNavBar: false, screen: const FeedbackDialog()),
           ),
-          const ListTile(
-            leading: Icon(Icons.science_outlined),
-            // onTap: () => pushScreen(context, withNavBar: false, screen: const GradeAveragesScreen()),
-          )
         ],
       ),
     );