vanshikasharma21/startup-hub ? reverse-engineered prompt

Build me a full stack web app called StartupHub where people can sign up, log in, and log out, then browse a collection of startups in one place. I want users to be able to add a startup, see it listed with the rest, open a detail page for each one, and click through to the startup’s official website. Please make it feel clean and easy to use on both desktop and mobile, with a simple modern layout.

Use a React frontend and a Node and Express backend with MongoDB for storage. Set up the basic REST API, authentication, and database connection so the app actually works end to end. If you need to check current docs for anything, go ahead and look them up. I mainly want a polished MVP that feels complete, works smoothly, and is easy to run locally.