Add a shared normalize_download_category helper (with CATEGORY_MAP) in Python
and use it in get_download_directory to prefer redirected paths and to rank
diffusion_models above legacy unet folders. Mirror the same normalization in
the JS downloadTargetMethods, applying it consistently when coalescing
downloadDirectories, building dropdown keys, and reading/writing selections.
Also fix display labels to use 'diffusion_models' instead of 'unet'.
Dariusz L
7a1473b58e