Adaptive presentment currencies

[zkat]

For Stripe, some payment methods are dependent on the presentment currency of the payment. For example, iDEAL is only available for payments in EUR, so payments in USD won't show that as a possible payment method.

I don't have a full solution off the top of my head right now, but we should design something such that studios are able to adapt to clients' preferences or needs, as far as payment methods and presentment currencies go, and we should do it in a way that's not complicated for either party.

This is a very tricky thing to do right, because it involves dealing with exchange rates, and adapting to potential issues such as rapid (>2%) exchange rate drift during the lifetime of an invoice. Our current currency conversion is best-effort and even if we were using https://striperates.com/, there's no guarantee that's the exact rate stripe will ultimately use for conversion.