feat(bookings): allow cancelling booking confirmations

Add API endpoint to revert confirmed bookings to pending status
Add unconfirm buttons to the bookings list and confirmation page
Update inventory summary when a confirmation is cancelled

shared/booking.ts

@@ -145,6 +145,11 @@ export interface ConfirmBookingResponse {
   ticketReceiptWhatsApp: WhatsAppDeliveryResult
 }
 
+export interface CancelBookingConfirmationResponse {
+  booking: PublicBooking
+  alreadyPending: boolean
+}
+
 export function isBookingStatus(value: string | null | undefined): value is BookingStatus {
   return value === 'pending' || value === 'confirmed'
 }