NEW YORK — When it comes to animation art, there is one name that has led the market since the late 1930s. Based in Los Angeles at that time, the animators at Walt Disney Studios cranked out many thousands of celluloid images, or cels, of Mickey Mouse and other now-beloved characters for cartoons and film shorts. It released its first animated feature film, Snow White and the Seven Dwarfs, just before Christmas in 1937. That film was a huge hit, but were it not for another California company — Courvoisier Galleries — much of the original artwork generated to create it might have been lost to history.