pub async fn download(
model: &HubModel,
option_id: Option<&str>,
dest_dir: &Path,
progress: Option<ProgressCallback>,
cancel: Option<Arc<AtomicBool>>,
) -> Result<PathBuf, String>Expand description
Stream-download a model’s variant into dest_dir, emitting
stage: "download" progress, then verify sha256 if the option pins one.
Streams to a .part file and renames on success.