Siddharth-Tayal/zenith-shop ? reverse-engineered prompt

Build me a backend for a shop app that can handle users, products, and orders in a way that feels fast and reliable even under heavy traffic.

I want one gateway that all requests go through, with login protection, simple rate limiting, and routing to the right service. The auth part should let people sign up and log in safely, and the product part should store items, let me create and update them, and cache product reads so the catalog feels quick. The order part should place orders and update stock in the background so the system stays responsive. Use a message queue for the order and stock syncing, and make sure the services wait until their databases and cache are ready before starting.

Please set it up so I can run everything locally with one command using Docker, and include a couple of simple test scripts to check the auth flow and product caching behavior. If you need to look up current docs online, go ahead.