A federal judge on Thursday told Stephen K. Bannon, a longtime adviser to former President Donald J. Trump, to surrender by July 1 to start serving a four-month prison term imposed on him for disobeying a subpoena to give testimony to the House committee that investigated the Jan. 6, 2021, attack on the Capitol. After Mr. Bannon was sentenced in October 2022 on contempt of Congress charges, Judge Carl J. Nichols, who has overseen the case, allowed him to remain free while he appealed. Last...