PlanResponse

{
    "plan_id": "string",
    "title": "제주도 겨울 여행",
    "thumbnail": "string",
    "start_date": "2026-01-04",
    "end_date": "2026-01-08",
    "duration_days": 0,
    "member_count": 0,
    "collection_count": 0
}