Enable volume bucket resampling for Parquet export

[NickS785]

Summary

• add a shared normalize_resample_params helper that lets resample rules opt into volume bucket aggregation
• update FastScidReader and async wrappers to honor the new volume-bucket parameters when exporting or loading data
• extend the async SCID reader tests to cover volume shorthand parsing and conflict validation

Testing

• pytest tests/test_async_scid_reader.py

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https://chatgpt.com/codex/tasks/task_e_690765021130832a88483652fee5373d