[WIP] Implement black horse mall project features

[Copilot]

• Explore repository structure and understand requirements
• Create parent POM with Spring Boot 3.x + Spring Cloud dependencies
• Create hm-common module (shared DTOs, exceptions, utilities, JWT auth)
• Create item-service module (product catalog CRUD)
• Create user-service module (user management and login)
• Create cart-service module (shopping cart with Redis)
• Create trade-service module (order management)
• Create hm-gateway module (API gateway with authentication filter)
• Create SQL init scripts for each service
• Build and verify the project compiles successfully

Original prompt

黑马商城项目实战