Feature request: Add "max" option when swapping from fedimint/onchain to self custodial lightning balance

[ghost]

When swapping from fedimint or onchain to self custodial, there are the onchain fees or the fedimint fees, if you want to move the whole balance its hard to gauge what the fees will be and you usually have to swap multiple times to get the whole balance through.

It would be nice if there was some button "max" that would automatically do the full balance minus whatever fees are necessary, maybe with an extra screen to confirm what the final fee is/what balance you are actually swapping into your channels.

[AnthonyRonning]

You should be able to type the full amount that's shown there, and it'll do the correct calculations.

But I agree a dedicated button is needed, we used to have it but changed the UI for the swaps.