feat(ui): display purchaser details on receipt and seat pages

Show customer name and phone number in a new panel
Add English and Chinese translations for the purchaser label

app/composables/useLocale.ts

@@ -121,6 +121,7 @@ const messages = {
     'receipt.recipient': 'Recipient',
     'receipt.recipientPhoneLabel': 'Recipient Phone',
     'receipt.guest': 'Guest',
+    'receipt.purchaser': 'Purchaser',
     'receipt.seatsReady': 'Seats ready',
     'receipt.seatsReadyDescription': '{count} {seatLabel} ready to send.',
     'receipt.copied': 'Copied to clipboard.',
@@ -270,6 +271,7 @@ const messages = {
     'receipt.recipient': '接收人',
     'receipt.recipientPhoneLabel': '接收人电话',
     'receipt.guest': '宾客',
+    'receipt.purchaser': '购票人',
     'receipt.seatsReady': '座位已准备好',
     'receipt.seatsReadyDescription': '{count} 个{seatLabel}已准备发送。',
     'receipt.copied': '已复制到剪贴板。',