S2S from the marketing site or signup page. Requires the same Bearer JWT as other /v1/internal routes (HS256). admin_id is not required. recorded_from is the page: landing (website) or signup. When visitor_id already exists it is reused and no new visitor is created. When visitor_id is missing, invalid, or not yet stored a visitor is created. Optional UTM fields are stored as a touchpoint; if none are provided the touchpoint is recorded as source=direct. A new touchpoint row is inserted only when the channel or page differs from the visitor's latest touchpoint.