Release 0.3.1

• Split structured pipeline console logs between stdout and stderr so regular progress messages and error records remain independent in SLURM output files.
• Add a unit test covering stdout/stderr routing for structured pipeline logging.
• Fix mypy compatibility for optional pyarrow.parquet imports in sliced selection writes.
• Keep the PyYAML import ignore compatible across typed and untyped environments.
• Pin the development mypy dependency to 1.19.1 to avoid the mypy 2.1.0 internal error observed in pre-commit CI.