Export Parquet x 6 (new format)

[jameshgrn]

Export new Parquet format for all 6 regions. Blocked by #34.

[jameshgrn]

Implementation complete in src/sword_duckdb/export.py:939-1036. GeoParquet with snappy compression, one file per table per region. Run with:

python scripts/maintenance/export_sword.py --source data/duckdb/sword_v17c.duckdb --format parquet --all

Blocked on lake fixes (#17, #19) before final export run. Leaving open until files on disk.

[jameshgrn]

Exports completed.

[jameshgrn]

GeoParquet exports (all 6 regions) included in v17c-beta.0.0.1 download on Google Drive.