Currency codes accepted for a delegation. Lowercase, mirroring the
backend's @IsIn(['usd','eur','usdc','eurc']) constraint on
POST /api/v1/delegation/create and the Python SDK's DelegationCurrency.
Card providers use 'usd'/'eur'; erc4337 uses 'usdc'/'eurc'.
Currency codes accepted for a delegation. Lowercase, mirroring the backend's
@IsIn(['usd','eur','usdc','eurc'])constraint onPOST /api/v1/delegation/createand the Python SDK'sDelegationCurrency. Card providers use'usd'/'eur'; erc4337 uses'usdc'/'eurc'.