* fix: prevent auto-update from downgrading prerelease/dist-tag versions
The auto-update checker was incorrectly updating pinned prerelease versions
(e.g., 3.0.0-beta.1) and dist-tags (e.g., @beta) to the stable latest version
from npm, effectively downgrading users who opted into beta.
Added isPrereleaseOrDistTag() check that skips auto-update when:
- Version contains '-' (prerelease like 3.0.0-beta.1)
- Version is a dist-tag (non-semver like beta, next, canary)
Fixes#613
* refactor: export version helpers and import in tests
Address review feedback: export isPrereleaseVersion, isDistTag, and
isPrereleaseOrDistTag from index.ts and import them in tests instead
of duplicating the logic.
Jason Kölker