relayer fee should be higher than tx gas fee
The fee received by the relayer should always be higher than the gas cost to submit the tx. Gas cost is the product of gas (which is fixed at around 42k for the call to `claim()`) and gas price, which is set by the relayer but it also based on current network conditions.

Two solutions:
- before submitting a tx, check the current gas price we'll use and calculate the gas fee based on that, and ensure the fee received will be higher
- change the relayer commission to be a fixed fee instead of a percentage of the swap value. this fee should always be higher than the gas fee will be even if the gas price pumps.

Will probably go with the second, since there's the added benefit of users not doing a small swap first to get some ETH in a fresh wallet, then doing a larger swap from there.