Add transparent background support for AI image generation

Hello,

Please add an option to generate images with a transparent background when the selected AI model supports it.

A simple “Transparent background” toggle in the image generation settings would make this easy to use. Ideally, it should request native transparency from the model rather than generate an opaque image and remove the background afterward.

This would be especially useful for creating icons, illustrations, stickers, and standalone objects that need to blend into a design without a rectangular background.

Expected behavior:

• Show the option when the selected model supports transparent output.

• Preserve actual transparency when placing the generated image on the canvas and exporting it as PNG.

• Produce a genuine alpha channel—not a checkerboard pattern rendered into the image.

The key benefit is getting a ready-to-use asset directly inside Figma, without a separate background-removal step or manual cleanup around the edges.