yasirlashari/mern-register ? reverse-engineered prompt

Build me a simple MERN app for user registration and sign in.

I want a clean frontend where someone can create an account, log in, and see a basic protected page after signing in. On the backend, set up the routes, database connection, and user handling so registrations are saved properly and passwords are stored safely. If it makes sense, add email notifications for registration or verification since this project looks like it may use Nodemailer.

Keep the UI straightforward and easy to use, nothing fancy, just polished and functional. Please wire up the frontend and backend so they work together, and include the basic setup needed to run the app locally. If you need to check current docs online for anything, go ahead.