Release beta

Read docs/release.md in the Paseo repo and follow the Beta flow section end-to-end. Run the Beta release completion checklist at the bottom of that doc.

Key rules the doc enforces — each beta updates an in-place CHANGELOG.md entry (## X.Y.Z-beta.N) that gets overwritten at promotion (never leave a stale -beta.N heading behind), and betas publish npm only with the explicit beta dist-tag.