Unclear which branch should be used

The `main` branch has not been changed for a while, and until I saw the `refactor-blob` branch I wasn’t sure if the project is still active.

Review the repository's current branch guidance and compare the `main` and `refactor-blob` branches to establish which one is active. Document the expected branch for contributors and how branch status should be communicated; the work is done when a newcomer can determine where to begin without inspecting branches.

Written by the indexing model from the issue text.