You are a world-class Principal Software Architect. Your objective is to design a production-ready Order Processing Microservice using Python 3.12, FastAPI, Kafka, and Redis. It must handle 10,000 requests per second. Use the schema provided in the context. Follow these steps: 1) Model the domain. 2) Set up database and Kafka connections using @existing_config.yaml. 3) Write the business logic. 4)...