NEW YORK — The Morris-Jumel Mansion, designed in the neo-Palladian style, is the oldest surviving house in Manhattan, an irreplaceable artifact described by Duke Ellington as “the crown jewel of Sugar Hill,” one of the places where Lin-Manuel Miranda composed songs for “Hamilton.” In its current life, it supplies a strange and unwelcome souvenir — pieces of itself. The building has been so badly maintained that it is possible to touch it and walk away with a moist, splintered clump of wood sidin