Get the profile of one ETF

Returns the current profile of one exchange-traded fund as a snapshot: at most one row, or an empty data array when the symbol is not a fund the provider covers (a stock ticker and an unknown symbol both return empty). expenseRatio is an annual percentage ("0.09" means 0.09%), and each sectorsList exposure is a percentage of the fund. nav and assetsUnderManagement are strings in navCurrency. avgVolume and holdingsCount are integers; physical-commodity funds report holdingsCount 0. assetClass is the provider's label as published (observed values include Equity, Fixed Income and Commodities) and is not a fixed set. updatedAt is the provider's last refresh time in UTC. Access is granted per account; keys without it receive 403 POLICY_DENIED.