fix: harden booking and meeting flows

lib/booking/customerView.ts

@@ -0,0 +1,25 @@
+import type { BookingRequest } from "@/payload-types";
+
+/** Explicit allow-list at the server/client boundary, including relationships. */
+export function customerBookingView(booking: BookingRequest) {
+  const offer = typeof booking.offer === "object" ? booking.offer : null;
+  const event = typeof booking.linkedEvent === "object" ? booking.linkedEvent : null;
+  const alternative = booking.proposedAlternative;
+  return {
+    id: booking.id,
+    date: booking.date,
+    startTime: booking.startTime,
+    endTime: booking.endTime,
+    status: booking.status,
+    appointmentType: booking.appointmentType,
+    offer: offer ? { title: offer.title } : null,
+    linkedEvent: event ? { slug: event.slug, isOnline: event.isOnline } : null,
+    proposedAlternative: alternative ? {
+      date: alternative.date,
+      startTime: alternative.startTime,
+      endTime: alternative.endTime,
+    } : null,
+  };
+}
+
+export type CustomerBooking = ReturnType<typeof customerBookingView>;