Source-Controller/Ecommerce-Site ? reverse-engineered prompt

Build me a simple e commerce shopping site in React that feels like a real online store. I want a clean home page with products shown in cards, a way to open a product and see more details, and a shopping cart where people can add, remove, and update items before checking out. Make it easy to browse and navigate between pages, and keep the design modern and responsive so it works well on phone and desktop. Use the existing React app setup, make sure it starts with npm start, and leave it in a state where I can run tests and build it for production too. If you need to check the latest React docs or best practices while wiring things up, go ahead and do that.