Lets ComfyUI fetch the models a workflow needs directly on the server,
so users no longer have to locate each file and drop it into the correct
folder by hand.
Crucially it supports gated HuggingFace repositories: the user logs in
once via HuggingFace, after which the server can download models that
require license acceptance or authentication — previously a manual,
error-prone step. The frontend can surface per-model availability and
download progress through the accompanying API.
