A designer in Mexico City invoices a client in New York in dollars, gets paid into a digital wallet, and covers her rent in pesos. Until recently, she found out what a month of work was actually worth only after the money had landed and been converted, by which point the exchange rate had already done its damage. Over a year, that uncertainty adds up. A contractor who quotes in one currency and budgets in another is running a small treasury operation without a finance team behind her. She has…