ConAgra Foods Inc. has scored a decisive victory in its battle against a $180 million verdict a federal jury returned following an accident that left three workers severely injured. The U.S. Supreme Court on Monday declined to review a ruling that released Omaha, Neb.-based ConAgra from liability for any part of the verdict. The ruling had been challenged by the injured workers and an independent contractor, West Side Salvage Inc. in Atkins, Iowa, hired to salvage grain from a clogged ConAgra elevator at a facility …