Rename the in-root loader path response field from `file_path` to
`loader_path` (matching compute_loader_path), and persist it on
asset_references so the API reads it directly instead of re-resolving
against every registered model-folder base per request.
- add loader_path column (migration 0006) populated at scan/ingest from
the already-computed loader path
- response prefers the stored value, falling back to compute for rows
written before the column existed
Buckets sharing a base directory (e.g. diffusion_models and a custom
unet_gguf) tagged every file in the directory regardless of whether the
bucket could load it, so .safetensors files were tagged
model_type:unet_gguf and vice versa. Carry each bucket's registered
extension set through get_comfy_models_folders and only emit a
model_type tag when the file extension matches, keeping the empty-set
match-all convention from folder_paths.filter_files_extensions.
Files under a model base matching no bucket now keep only the models
tag instead of every directory-matching model_type tag.
