A four-panel mural now stretches across the boarded-up windows of the long-vacant Renaissance Building on Otto Boulevard in Chicago Heights, transforming a symbol of downtown decline into what city and gallery leaders are calling a spark for renewal. The mural, unveiled on August 22, was painted by artist Javier Chavira and commissioned by Union Street Gallery, located directly across the street at 1527 Otto Blvd. Chicago Heights Mayor David Gon…