Where to send the user after a successful payment. Set this on the
paywall (default for every price) or per-price (overrides the default).
type=0 (alias "quiz") — redirect to a quiz; id is the quiz_id.
type=1 (alias "paywall") — redirect to another paywall; id is
the paywall_id (great for upsell flows: free → premium upsell).
Both numeric and semantic forms of type are accepted; the backend
normalises them. Omit the object entirely (or pass null) to use the
platform default (return to the quiz the user came from).