WASHINGTON — President Joe Biden has two seats to fill on the D.C. Circuit, the influential appeals court in the nation’s capital that regularly feeds judges to the U.S. Supreme Court.They are among the roughly 10% of federal judgeships that are or will soon be open, giving Biden his first chance to make his mark on the American judiciary.Barring an improbable expansion of the Supreme Court, Biden won’t be able to do anything about the high court’s entrenched conservative majority any time soon. Justice Clarence Thomas, at …