Ignore: 🐛 Modify Device Token Management Policy

[psychology50]

작업 이유

This work resolves a push notification error caused by duplicate device tokens.

Currently, the {deviceId, token} pair's uniqueness isn't enforced, leading to the following issue:

1. User 1 sign in on Device A.
2. User 2 sign in on Device B.
3. When User 2 sends a chat message in chatroom where User 1 is joined,
   they receive push notifications intended for User 1 via their token.

작업 사항

1️⃣ Improved Registration Logic

• Return a 409 Conflict error if an activated token with a different deviceId exists.
• Update deviceId when transferring token ownership.

2️⃣ Clarification Device Token Register Business Policy

• Each {userId, deviceId} pair can register new tokens but activate only one.
• token must be unique in table
• Tokens and {deviceId, token} pairs must be unique.
• Existing tokens update ownership and last login.
• New tokens are added if not already registered.
• Return 409 if a token exists for another deviceId.

리뷰어가 중점적으로 확인해야 하는 부분

1. Appropriateness of Business Rule Implementation

• Does DeviceTokenRegisterService align with the requirements?
• Is exception handling, especially for duplicate tokens, valid?

2. Domain Role Separation

• Are entity and domain service roles appropriately divided?
• Do unit and integration tests validate the core domain logic?

3. Token Ownership Transfer

• Is exception handling for mismatched deviceId valid?
• Are ownership update scenarios correctly handled?

발견한 이슈

1. Domain-Service vs. RDB Responsibility

• DB constraints should be verified in the domain-rdb module.
• Current tests extend beyond the domain service's responsibility.