[25.02.08 / TASK-109 / TASK-94] Feature - 샘플 유저 로그인 로직 추가, 신규 유저 slack noti 추가#17

Nuung merged 2 commits intomainCheck-Data-Out/velog-dashboard-v2-api:mainfrom

feature/sample-user-and-notiCheck-Data-Out/velog-dashboard-v2-api:feature/sample-user-and-notiCopy head branch name to clipboard