Event ticket QR codes

Auto-generated QR codes on every event ticket — emailed at purchase, viewable in the donor portal, and printable for the few attendees who still print tickets. The QR encodes a signed token tied to the specific ticket purchase, so it can't be forged or reused. Pairs with the mobile check-in flow for fast door scanning. Replaces the "please let me check the will-call list" experience that ruins event entry.