Basic Real-Time Chat App with Socket.io

Create a simple real-time chat application using React (Vite) for the frontend, Node.js + Express for the backend, and Socket.io for real-time communication.

Features to Implement:

- User Connection Handling: Show when a user joins or leaves the chat.
- Real-Time Messaging: Messages should instantly appear for all connected users.
- Basic UI: A simple chatbox with an input field and a send button.
- Broadcast Messages: Notify all users when someone sends a message.

Tech Stack:

- Frontend: Vite + React, Socket.io-client.
- Backend: Node.js + Express, Socket.io.

Optional: Add usernames, typing indicators, or message history.

Socket.io - https://socket.io/docs/v4/
Vite React - https://vite.dev/guide/