[codex] add sklt npm publish flow

[johnnyhuy]

This adds a complete npm publish pipeline for sklt, including automatic publishes from GitHub releases, manual publishes from an explicit ref, and dry-run verification paths for both CI and local development.

The repository already built a Node-compatible CLI bundle, but publishing still depended on manual npm publish execution and there was no repeatable way to validate the package payload before release. That also made it easy for packaging drift to slip past CI. In addition, the npm-facing command and package naming needed to be simplified to sklt so npx sklt works directly.

This change renames the npm package and bin to sklt, updates help text and docs to match, adds a dedicated npm Publish workflow with release and manual-dispatch triggers, and introduces a reusable mise run npm-publish-dry-run task. CI now exercises that dry run so package publication is validated continuously, while the publish workflow skips already-published versions and supports manual dry-run execution with a safe fallback dist-tag.

Validation:

• mise run npm-publish-dry-run
• mise run ci