원화 환율 조회 스킬. 한국어 지시 예: "오늘 달러 환율 알려줘", "2026-03-01 EUR 환율 조회", "이번 달 엔화 평균 환율 보여줘". Retrieves KRW exchange rates from Seoul Money Brokerage Services (서울외국환중개), supports 53 currencies, and can return daily or monthly average rates. Falls back to the prior business day when the requested date has no published rate. Usage: /itda:exchange-rate [date|month] [currency]