Start a real-human verification session

Begin creating a real-human (LivenessFace) asset group. Returns an H5 link the end user opens to complete a one-time face verification. After they finish, the verification page redirects their browser back to an OrcaRouter callback (handled for you), and the new group is registered. Poll GET /asset/real-human/sessions/{session_id} for the result. The end user's device does not need to be logged in.