feat: 이달의 현황 API lastMonthRank를 스냅샷 단건 조회로 변경#405

KoSeonJe merged 2 commits intodevelopCOW-dev/ddingdong-be:developfrom

refactor/feed-monthly-status-snapshot-lookupCOW-dev/ddingdong-be:refactor/feed-monthly-status-snapshot-lookupCopy head branch name to clipboard