Asynchronous AVIF saver using ComfyUI's native AVIF encoding path. Encoding is performed by a detached worker thread, so the workflow is not held up by AVIF encoding.
The final AVIF is sent through ComfyUI's normal output preview path after the
background encode completes. The included frontend hook waits until the image
is attached to the node and calls ComfyUI's existing setSizeForImage() so a
newly displayed preview is not stuck at the minimum preview height.
The SVT-AV1 preset is configurable from 0 through 13 and defaults to 8.