Changelog maintenance

For published changes, see the project's release history or the complete repository changelog.

Contributors and maintainers should record each user-visible change under Unreleased in the repository changelog:

1. add an entry under Unreleased;
2. group the entry under the appropriate heading;
3. mention compatibility or migration notes when behavior changes;
4. move entries into a versioned section during release preparation.

The project follows Semantic Versioning and the compatibility expectations described in the release policy.