pandas>=1.5
# fsspec + driver only needed for cloud staging paths:
#   s3://   → pip install fsspec s3fs
#   gs://   → pip install fsspec gcsfs
#   abfs:// → pip install fsspec adlfs
# SQL backend uses sqlalchemy (usually already installed via other components).
# iceberg backend requires `pip install 'pyiceberg[pyarrow]'` — only imported
# on demand when write.kind == 'iceberg'.
