feat: send ticket receipts via WhatsApp and normalize phone numbers

Add WhatsApp API integration for automated receipt delivery
Enforce country codes for all phone number inputs (defaults to +60)

shared/booking.ts

@@ -116,6 +116,21 @@ export interface CreateBookingResponse {
   whatsappUrl: string
 }
 
+export interface WhatsAppDeliveryResult {
+  sent: boolean
+  skipped: boolean
+  recipientPhone: string
+  apiRecipientPhone: string
+  messageId?: string
+  error?: string
+}
+
+export interface ConfirmBookingResponse {
+  booking: PublicBooking
+  alreadyConfirmed: boolean
+  ticketReceiptWhatsApp: WhatsAppDeliveryResult
+}
+
 export function isBookingMode(value: string | null | undefined): value is BookingMode {
   return value === 'table' || value === 'seat'
 }