PATERSON — More than 200 students from Paterson’s Harp Academy marched against gun violence on Monday morning in honor of classmate Robert Cuadra, the 18-year-old who was killed in the crossfire of a gang shooting in January while he was bringing home groceries. Among the marchers was senior Laura Valle, who described Cuadra as a longtime friend who was outgoing and “crazy funny.” Cuadra wasn’t the only friend she lost to gun violence during her high school years, Valle said.