eSIM setup and configuration

// Wrong: the rate ages while the customer reads the screen.
const quote = await quoteEsim(plan, account);
await showConfirmation(quote);          // customer goes to find their passport
await buy(quote.fxQuoteId);             // 409 esim_fx_quote_required

// Right: quote, confirm, buy — and re-quote if they were slow.
let quote = await quoteEsim(plan, account);
const confirmed = await showConfirmation(quote);
if (!confirmed) return;

if (Date.parse(quote.expiresAt) - Date.now() < 15_000) {
  quote = await quoteEsim(plan, account);   // show the new figure before charging
}
await buy(quote.fxQuoteId);