Fix ruff errors: remove unused import and extraneous f-string prefix

- Remove unused `NonEmptyStr` import in datasets.py (F401)
- Remove extraneous `f` prefix on string literal in download.py (F541)

https://claude.ai/code/session_01W8psU8qD4io2AoWLvFxyJh

Author: claude

src/ndi/cloud/api/datasets.py

@@ -16,7 +16,7 @@
 from pydantic import SkipValidation, validate_call
 
 from ..client import APIResponse, CloudClient, _auto_client
-from ._validators import VALIDATE_CONFIG, CloudId, NonEmptyStr, PageNumber, PageSize
+from ._validators import VALIDATE_CONFIG, CloudId, PageNumber, PageSize
 
 _Client = Annotated[CloudClient | None, SkipValidation()]
 

src/ndi/cloud/download.py

@@ -663,7 +663,7 @@ def downloadGenericFiles(
         if zip_result and report["downloaded_filenames"]:
             import zipfile as _zipfile
 
-            zip_name = target / f"exported_generic_files.zip"
+            zip_name = target / "exported_generic_files.zip"
             with _zipfile.ZipFile(zip_name, "w", _zipfile.ZIP_DEFLATED) as zf:
                 for fname in report["downloaded_filenames"]:
                     zf.write(target / fname, fname)