`_resolve_frontend_root` honours `CreateTicket.frontend_url` when its
origin is one of LNBITS_CORS_ALLOWED_ORIGINS, the LNbits base URL or
LNBITS_CUSTOM_FRONTEND_URL (400 otherwise — a silent fallback would send
the buyer to the wrong app), and falls back to request.base_url as before.
Under that root the fiat path now parameterises the hosted checkout via
`extra["checkout"]` (lnbits StripeCheckoutOptions): success_url
`/events/{id}?checkout=success&tickets=<ids>`, cancel_url
`/events/{id}?checkout=cancelled`, customer_email, an event-named line
item and event_id/quantity/ticket_ids metadata. Ticket ids are minted
before the invoice so the success URL can carry them (the payment_hash
only exists afterwards). ticket_base_url on the rows uses the same root,
so the emailed link lands in the webapp when the webapp was the client.
Purchases are gated on `effective_payment_methods(event)` (checked after
the free-ticket short-circuit, which charges nothing on any rail).
New anonymous `GET /events/api/v1/qr/{ticket_id}` returns a PNG of
`ticket://<id>` — port of upstream v1.6.8's endpoint without ticket-image
compositing — built at error-correction H with the instance QR logo
(`lnbits_qr_logo`) pasted in the centre, matching the client-side QRs.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EYwoAkZZmXMMmaBp4WGUBo
