券商 API資産 帳戶餘額帳戶餘額 GET /openapi/broker/assets/balance • 查詢帳戶資產相關資訊，包括：現金餘額、持倉市值、盈虧、購買力、應付利息等。 Request Responses200401417500OKUnauthorized: Authentication requiredA business logic error triggered when the request cannot be processed due to domain-specific constraints.Internal Server Error.