- Add test_s3_bucket_single_object_after_duplicates to verify only one S3 object exists
- Add tests for upload failure scenarios (invalid project/package, empty file)
- Add tests for orphaned S3 objects and database records cleanup
- Add S3 direct access helpers (list_s3_objects_by_hash, s3_object_exists, etc.)
- Fix conftest.py to use setdefault for env vars (don't override container config)
All 52 tests now pass.
- Add test_integration_uploads.py with 12 tests for duplicate upload scenarios
- Add test_ref_count.py with 7 tests for ref_count management
- Fix ArtifactDetailResponse to include sha256 and checksum fields
- Fix health check SQL warning by wrapping in text()
- Update tests to use unique content per test run for idempotency
