Add created/updated at time based filters for an order's fulfillments

As of API version 2025-07 you can now narrow the list of fulfillments returned by Order.fulfillments with an optional query argument that targets created_at and/or updated_at fields. The argument uses the same search syntax already familiar from other Admin API endpoints, for example:

fulfillments(query: "created_at:'2025-05-07T08:37:00Z'")
fulfillments(query: "created_at:>='2025-05-07T00:00:00Z' updated_at:<'2025-05-09T00:00:00Z'")

The field still returns a simple array—no pagination cursor needed—and behaves exactly as before if you omit query.