price is the whole story:
kind is product (with product_id), bundle (a combo, bundle_id) or credit
(credit_amount in integer COP). quantity is how many of the product or combo one ticket
earns. Ignore perks with is_active: false.
Adding a perk at checkout
count is capped at
the number of tickets of that ticket type in the order (two tickets, at most two perks).
After payment the holder receives the voucher in the ticket email and in the tickets app.
Nothing else is needed from the storefront.

