- isInvitation (nullable bool) on BilletBuyer instead of checking totalHT == 0
- Set isInvitation=true when creating invitation in controller
- Email subject/content based on order.isInvitation
- Invoice shows organizer as buyer when order.isInvitation
- Invitations list filtered by isInvitation=true
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
