Frances Vorne, a 19-year-old New York girl who calls herself The Shape, wound up 1944 with perhaps the best claim to an honor publicity agents fight desperately over: the crown as Pin-Up Girl of the Year. First the Associated Press in a rare moment of relaxation gave her the title. By last week The Shape had received even more dazzling recognition as the circle of her admirers expanded to include at least one segment of British officialdom. The British Ministry of Information saw her photograph in the London Daily Mirror, immediately cabled the U.S. for permission to use it in stimulating the morale of Britain's Army & Navy.