Noah Business Fee
data class NoahBusinessFee(val feeBase: String? = null, val feePct: String? = null, val fiatCurrency: String? = null)
Optional business (partner) fee applied to a Noah payout or payin.
JSON keys use PascalCase to match the Noah API wire format. The BFF forwards this object straight through to Noah, so the inner field names must stay PascalCase even though the surrounding request keys are camelCase.