WASHINGTON — The Supreme Court on Thursday allowed a 12-year-old transgender girl in West Virginia to continue competing on her middle school’s girls sports teams while a lawsuit over a state ban continues.The justices refused to disturb an appeals court order that made it possible for the girl, Becky Pepper-Jackson, to continue playing on her school’s track and cross-country teams, where she regularly finishes near the back of the pack.Justices Samuel Alito and Clarence Thomas would have allowed West …