### Task Summary `amber/src/main/python/pytexera/storage/dataset_file_document.py` currently has ~24% unit-test coverage. Add unit tests for `DatasetFileDocument` covering path parsing, environment-variable handling, presigned-URL retrieval, and binary file download (all failure paths included). ### Task Type - [x] Testing / QA
Task Summary
amber/src/main/python/pytexera/storage/dataset_file_document.pycurrently has ~24% unit-test coverage. Add unit tests forDatasetFileDocumentcovering path parsing, environment-variable handling, presigned-URL retrieval, and binary file download (all failure paths included).Task Type