Show embedded-workflow images (.png/.webp) alongside .json workflows and allow drag-and-drop into ComfyUI

From Discord feature-requests thread <#1546123218967072839> (Sep 06, 2026):

Since ComfyUI workflows can also be embedded in .png and .webp images, Stability Matrix could:

1. Show those workflow-embedded image files alongside .json workflow files in the workflow browser.
2. Allow dragging such an image into ComfyUI to load its embedded workflow.
3. Alternatively, work similarly to the Checkpoints browser's preview image handling.

Source: https://discord.com/channels/1115555685476868168/1546123218967072839