At public ceremonies and private meetings, Milton I. Shadur always sat at the right hand of Chicago’s top federal trial judge.“That was not by accident,” the man currently serving in that position, Chief U.S. District Judge Ruben Castillo, said today. “We relied on him very much.”Castillo noted it was only timing — a jurist must be younger than 65 when he or she gets to the front of the seniority line — that prevented Shadur from claiming the title of chief judge himself.But Shadur …