Event RSVP + ticketing

Build a hosted-event page with RSVP or paid ticketing.

Core features:
1. Event page: cover, description, location/map, agenda
2. RSVP (free) or Stripe ticket purchase with tiers
3. QR ticket by email, checkin app for door staff
4. Attendee list export, refunds

Data: events, tickets, attendees, checkins.
Must-haves: capacity limit, mobile checkin scanner, GDPR-safe attendee list.