BillingSummary

import BillingSummary from "@dertour/ui/components/common/BillingSummary/BillingSummary"

Billing summary cards (KWRP-225): total cost, paid to date and the outstanding balance, as three stat cards (the design's billing header). Render-only — the remaining-to-pay card is emphasised. The balance is Travel Box-dynamic and passed in from the `getBookingBalance` seam.