The same Order as GET /merchant/orders/{id}, looked up by the orderReferenceId you sent when
the order was created — for a webhook or a return that names your reference, or a store that never
stored the Qasimha id. Requires scope orders:read.

The reference is the path remainder, so ORDER/2026/1 is /by-reference/ORDER/2026/1;
percent-encoding is also accepted. Case-sensitive, exact match. A reference used by another
merchant, or never used, answers 404.