frontend: Activity: Add unique aria-labels to complementary landmarks

Signed-off-by: Sagar Choudhary <sagar6203620715@gmail.com>

Author: Sagar-6203620715

frontend/src/components/activity/Activity.tsx

@@ -248,6 +248,7 @@ export function SingleActivityRenderer({
     <ActivityContext.Provider value={activity}>
       <Box
         role="complementary"
+        aria-label={typeof title === 'string' ? title : `Activity ${index + 1}`}
         sx={{
           display: minimized && !isOverview ? 'none' : undefined,
           gridColumn: '2 / 3',