为头像添加圣诞帽（图像到图像）

Using the user-uploaded reference image as the base, add a classic Christmas Santa hat to the subject.

Style match: preserve the original art style exactly (2D/3D/photorealistic/anime/cartoon), keeping identity, facial features, hairstyle, colors, shading, and overall composition unchanged.

Hat design: traditional Santa hat (red felt with subtle fabric texture, white fluffy trim, white pom-pom). Place it naturally on top of the head, aligned to head angle and hairline. Respect perspective, scale, and head shape.

Integration: match the existing lighting, shadows, highlights, linework, and rendering style. Add realistic contact shadows where the hat touches hair/forehead. Do not alter the face, hair, background, clothing, or any other elements.

Output: square (1:1) avatar, crisp and clear at small profile-picture size.