theharsh29/chat-app ? reverse-engineered prompt

Build me a real time chat app where people can sign in, see who is online, and send messages instantly. I want both one to one chats and group chats, so users can talk privately or create a group and message everyone at once.

Make it feel simple and modern, with a clean chat layout, a conversation list, a message area, and clear indicators for unread messages and online status. It should update live without needing refresh, and messages should show up right away for everyone in the chat.

Please use the existing MERN style setup in this project and Socket.IO for the live messaging part. If anything is unclear, look up the current docs online and wire it up in a practical way. Also make sure the app works smoothly in both the client and server parts, with basic error handling and a good first run experience.