Ignore: 🐛 Reduce distributed lock duration by separating domain logic

[psychology50]

작업 이유

#237

The current chat room join implementation had an issue where distributed locks were held for too long, as they included both business validation and data retrieval for responses.

This refactoring aims to:

• Minimize distributed lock duration by isolating core join logic
• Prevent race conditions with proper lock management
• Improve code maintainability through clear separation of concerns

작업 사항

1. Extracted core join logic into ChatMemberJoinOperation

   • Moved all business validations into a single, focused class
   • Reduced lock duration by separating response data preparation
   • Improved validation with clear input parameters

2. Optimized ChatMemberJoinService

   • Shortened lock duration by focusing on critical section
   • Loads required data efficiently to minimize lock time
   • Clear separation between join logic and response preparation

3. Added comprehensive test coverage

   • Pure domain logic testing for operation
   • Integration tests verifying lock behavior

리뷰어가 중점적으로 확인해야 하는 부분

I know, I know. I get that it was inappropriate to suddenly carry out such a large-scale change. But I've never liked the fact that the Aggregate Root references the User object in another ChatMember as an entity. This time, I had to change it to a value reference because otherwise, it could cause a serious delay in chat room joins.

발견한 이슈

• none