fix: skip unreadable audio files during batch processing

[mbsantiago]

Summary

Skip unreadable audio files during batch directory/file-list processing instead
of failing the whole run.

Changes

• catch LibsndfileError when creating recordings in
  get_clips_from_files
• log a warning and continue processing the remaining files
• add a CLI regression test covering a directory with one valid file and one
  corrupted file

Testing

• uv run pytest tests/test_cli/test_process.py

Acknowledgements

Thanks to @SanderBud for raising this in issue #68.