Function finalize_local_gguf 

pub fn finalize_local_gguf(
    gguf_path: &Path,
    storage_root: &Path,
) -> Result<ActiveModelRecord, ModelError>

Register and activate a user-selected .gguf file at an arbitrary path.

Writes {model_id}.install.json under {storage_root}/Models/ (path is not copied), maps GGUF tensor pointers into the WAL, and transitions lifecycle → Active.