codingmonk-yt/chat-app ? reverse-engineered prompt

Build me a simple chat app in this React project that feels clean and modern.

I want a page where someone can see a list of chats or messages on the left or top, open a conversation, and send new messages in a chat box. It should look good on desktop and mobile, with a friendly layout, clear typography, and easy to use controls. Add a few sample conversations and messages so it feels complete right away, and make sure the interface updates smoothly when a new message is sent.

Keep it polished and practical, with a nice empty state, a message composer, and a basic header. If you need to check anything, look up the current React docs online and keep the implementation simple so it runs well with Create React App.