It is astonishing, particularly for those like Josephine DiSunno who were around when the Amagansett Fire Department was simply middle-aged, that it has now passed the century mark. Mrs. DiSunno, who was a charter member of the department’s ladies auxiliary, was among the many who took part in a celebratory parade on Saturday, which included delegations from departments from as far afield as Eastport and Ronkonkoma.