Booking Money Formatter

Shared Intl.NumberFormat-based money formatting for Money objects (smallest-unit amounts). Use `formatMoney(money)` for default 2dp display, or `formatMoney(money, { maximumFractionDigits: 0 })` for integer prices. Used by TicketMixEditor, BookingSummaryCard, ActivityBookingSidebar, ActivityCard, PropertyCard, and RatePlanSelector.