yvnks/sur ? reverse-engineered prompt

Build me a simple MERN social media app that runs locally and opens in the browser at localhost 3000.

I want a clean, working starter app with a frontend and backend wired together, connected to MongoDB, and easy to launch with one development command. Make sure the app feels like a real social media product, even if it’s basic, with a simple homepage and a place for users to sign in and see a feed or posts. Keep the UI clean and modern, and make the whole thing easy to understand and run without extra setup pain.

If anything is unclear, use sensible defaults and look up current docs online if you need to. Please make sure the project starts properly in development and the client and server talk to each other without errors.