* ci: add continuous delivery workflows for npm publishing
Add publish-next (auto-prerelease on push to main) and publish-latest
(manual stable release with Discord notification). Update CONTRIBUTING.md
to describe the trunk-based CD model.
* fix(ci): guard publish-latest against non-main dispatch
Reject workflow_dispatch runs from non-main refs to prevent
publishing unintended code or fast-forwarding main unexpectedly.
* chore: unify npm publish workflow
Alex Verkhovsky