Returns indicative FX rates for one or more currency pairs — reference values for display or estimation, not tradeable. Each pair returns three rates: the raw mid-market rate (naked), the card-channel margin-adjusted rate, and the wallet-channel margin-adjusted rate. For a binding rate that can be transacted on, use POST /v1/fx/quotes + POST /v1/fx/conversions. Pairs are 6-character codes (sell + buy, e.g. 'AUDGBP'). Partial-success returns HTTP 200 with per-pair errors in the body; omitting currencyPairs returns an empty result.