Cat hair is not an allergen.
People are allergic to the protein found in dander, and the saliva of cats and dogs.
After your gift quilts are made wash them, dry them, package them up in plastic or remove them from the house. No need for a warning label. This is not a nut or shellfish. lol I have lived with severe allergies all my life (bad enough to take shots), I also live in a house with two cats and two dogs. They are bathed once a week in baby shampoo and Downy. I am allergic to birds but sleep on a feather pillow too. I know I must have a death wish huh!