refactor(bookings): simplify capacity tracking to use seats

Replace 'pax' booking mode with 'seat'
Consolidate inventory summary to track only seat counts
Update database schema and UI for seat-centric capacity

app/pages/confirmation/[token].vue

@@ -3,7 +3,6 @@ import type { PublicBooking } from '~~/shared/booking'
 
 import {
   formatBookingCurrency,
-  getBookingModeLabel,
   getBookingStatusLabel,
   getTicketCatalogItem
 } from '~~/shared/booking'
@@ -54,18 +53,10 @@ const detailRows = computed(() => {
       label: 'PIC Phone',
       value: booking.value.personInChargePhoneNumber
     },
-    {
-      label: 'Booking Mode',
-      value: getBookingModeLabel(booking.value.bookingMode)
-    },
     {
       label: 'Ticket Category',
       value: ticketLabel.value
     },
-    {
-      label: 'Quantity',
-      value: String(booking.value.quantity)
-    },
     {
       label: 'Seats Covered',
       value: String(booking.value.seatCount)