Function decimal_to_scaled_u256 

pub fn decimal_to_scaled_u256(value: Decimal) -> Result<U256, &'static str>

Scales a [Decimal] amount to a 1e18 fixed-point [U256].

Used for unsigned fields like max_fee where negative amounts are not meaningful and the venue rejects negative encodings.

Errors

Returns an error if the value is negative, exceeds the accepted precision, or exceeds the unsigned 256-bit range after scaling.