why: release component autodoc for the whole docutils and Sphinx
extension family — transforms, readers, parsers, writers, nodes,
translators, builders, and domains — with cross-reference roles,
linked facts, and the fact-value chip-padding fix.

what:
- Bump all workspace packages 0.0.1a28 -> 0.0.1a29
- Date CHANGES entry for 0.0.1a29 (2026-06-07)
- Add 0.0.1a30 unreleased header