Merge main into PR 8 and preserve NKJP source

Add source: european_hplt_v3_pl (HPLT v3.0 Polish, top WDS bins, CC0) (#5)

Add source: govpl (gov.pl government press releases) (#9)

Add source: nkjp1m

Release v0.3.1 Europeana preview shard (#4)

Credit source expansion contributor

Remove generated Python cache files

Update v0.2.1 HF card release date

Release v0.2.1 metadata schema update

Add launcher for parallel HPLT filtering

Shard and parallelize HPLT filtering

Add progress logging to HPLT filtering

Add European HPLT Polish web filtering workflow

Add v0.3 source license review and quality mix workflow

Add phrase frequency stats and HF card snippet for Polish DynaWord

Squash: collapse LFS history to reclaim private storage