Add ticket system with QR scanner and PDF generation

- Add ticket validation and check-in API endpoints
- Add PDF ticket generation with QR codes (pdfkit)
- Add admin QR scanner page with camera support
- Add admin site settings page
- Update email templates with PDF ticket download link
- Add checked_in_by_admin_id field for audit tracking
- Update booking success page with ticket download
- Various UI improvements to events and booking pages

frontend/src/app/(public)/events/page.tsx

@@ -135,12 +135,14 @@ export default function EventsPage() {
                           <MapPinIcon className="w-4 h-4" />
                           <span className="truncate">{event.location}</span>
                         </div>
-                        <div className="flex items-center gap-2">
-                          <UserGroupIcon className="w-4 h-4" />
-                          <span>
-                            {event.availableSeats} / {event.capacity} {t('events.details.spotsLeft')}
-                          </span>
-                        </div>
+                        {!event.externalBookingEnabled && (
+                          <div className="flex items-center gap-2">
+                            <UserGroupIcon className="w-4 h-4" />
+                            <span>
+                              {event.availableSeats} / {event.capacity} {t('events.details.spotsLeft')}
+                            </span>
+                          </div>
+                        )}
                       </div>
                       
                       <div className="mt-6 flex items-center justify-between">