OKF sample bundles

The acme_retail, crypto_bitcoin, ga4, and stackoverflow directories are
copied unmodified from the Open Knowledge Format repository by Google LLC:
https://github.com/GoogleCloudPlatform/open-knowledge-format/tree/main/bundles

Copyright Google LLC. Licensed under the Apache License, Version 2.0 (see
LICENSE.md in this directory). The exact upstream commit is recorded in
SOURCE.json; refresh with `pnpm fixtures:refresh`.

They are used here only as test fixtures. Their inclusion does not imply that
Google endorses OKForest.
