Add the last seen feature to the project

hello contributors, I want someone to add the last seen feature, on disconnecting from socket.io, send the current time to backend and store it on Db which is MongoDB, shouldn't be hard, T am using react.js and node.js as frontend and backend in it. Ask me if you have any doubt.

Start by locating the socket.io disconnect handling in the React and Node.js parts of the project, then trace how user data is stored in MongoDB. Confirm how the current time should be represented and which user record receives it. Done means a disconnect persists the user's last-seen time in MongoDB.

Written by the indexing model from the issue text.