[web] Support multi-byte characters in online user name (#26882)

GitOrigin-RevId: 9547ed7df13fcf8bb51ddd8c3f59167c2099e4e6

services/web/frontend/js/features/ide-redesign/components/online-users/online-users-widget.tsx

@@ -86,9 +86,10 @@ const OnlineUserWidget = ({
 
 const OnlineUserCircle = ({ user }: { user: OnlineUser }) => {
   const backgroundColor = getBackgroundColorForUserId(user.user_id)
+  const [character] = [...user.name]
   return (
     <span className="online-user-circle" style={{ backgroundColor }}>
-      {user.name.charAt(0)}
+      {character}
     </span>
   )
 }