Scanning at scale — offline, Count mode and NFC

The scanner is built for big outdoor events where the network dies and iPads glare in the sun. Open /flow/scan and pick one of three modes:

• Scan — reads a pass and validates it on-device against a pre-downloaded, signed list, so it keeps admitting with zero network. Offline scans queue and reconcile when connectivity returns. The badge shows Online/Offline + how many scans are queued.
• Count — for free events, tap one big "+1" per wristband handed out. No camera, no QR, no readable screen needed — sun-proof. Each tap feeds the live gate count.
• NFC — tap an NFC wristband or phone (Android / rugged readers). No camera, no screen glare.

For a free event the wristband is the admission token; you count people in rather than scanning every pass.