Your refrigerator Rembrandts and Mary Cassatts could see their artwork gracing a Hallmark card. The greeting-card company, along with Crayola, is sponsoring the second annual Kids Card Contest. Children between the ages of 5 and 14 are invited to create original birthday cards - 12 of which will become part of a line of cards next summer. Entry forms will be available starting Feb. 28 from participating Safeway, Kmart, and WalMart retailers. Deadline for entries: March 14. For more information, call: 800-HALLMARK.