In a year of failures for art-related startups, Artsy CEO Carter Cleveland might be the last man standing. Walking into Artsy’s New York headquarters, 26 floors above Chinatown, feels like encountering a monumental blank canvas in a light-drenched artist’s studio. The walls are white. The furniture is white. On a bright spring morning, shadows slide across the desks of 140 employees as the sun traces Canal Street from east to west.