Docs refresh: merge the re-pointed v0.2.5 tag; document main since v0.2.5

docs: v0.2.5 includes all 20 sources in the tagged tree

Only document sources that are actually committed (#30)

Make release totals registry-driven (#29)

feat(data): add samorzad.gov.pl institutional corpus (#13)

feat(data): european_hplt_v3_pl expansion WDS bins 10-5 (+1.49M docs / 2.04B tok) (#12)

Release v0.2.3 with community HPLT contribution

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

Release v0.3.1 Europeana preview shard (#4)

Document live source-gate validation (#3)

Credit source expansion contributor

Update v0.2.1 HF card release date

Release v0.2.1 metadata schema update

Update HF card with v0.3 preview status

Squash: collapse LFS history to reclaim private storage