The previous pre-release versions (4.x.y-beta.N) caused two issues:
- semver.inc('4.0.0-beta.N', 'major') returns 4.0.0, not 5.0.0
- Pre-release numbers carried over (beta.61 -> beta.62 instead of beta.0)
Setting all versions to 4.0.0 (non-pre-release) ensures a clean major
bump to 5.0.0-beta.0. Also removes @workflow/swc-playground-wasm from
the changeset and pre.json since it is a private package.