[Task][Backend] User 관련 기능#2

### ISSUE
- Group: `server`
- Type: `feature`
- Detail: create funciton part logics

### TODO
1. [ ] 회원정보 조회, 수정 기능 구현
1. [ ] 회원정보 삭제(회원 탈퇴) 기능 구현

### Estimated time

### `3h`

### Labels
- Estimated time: `E: 3h`
- Group : `server`
- Urgency : `High`

No files, tests, routes, or entry points are named. Start by locating the server-side user feature, then determine the existing conventions for member-information retrieval, editing, and account deletion; done means all three TODO items are implemented and verified by the project's available checks.

Written by the indexing model from the issue text.