aarav2912/project ? reverse-engineered prompt

Build me a simple electronic marketplace where people can post items for sale or for purchase, and browse everything by categories that can nest into a hierarchy. I want users to be able to sign in, create listings, search or filter by category, and see a clean feed of current offers. Also add a private alert feature where someone can say they are interested in a certain category or item type without making that public, then get notified when matching items are listed for sale.

Please make it feel like a small but real app, with a working frontend and backend, basic data storage, and whatever support is needed for login, item listings, categories, and notifications. If you need to, look up current docs online for the best way to wire it together. Keep the experience simple and usable, and make sure the category structure and alerting flow actually work end to end.