remove: delete legacy GitHub Secrets NPM workflow

- Remove publish-public.yml (361 lines) that uses GitHub Secrets for NPM token
- Keep npm-publish-simple.yml that uses AWS SSM Parameter Store
- Consolidate to single secure workflow using OIDC authentication

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: PaulDuvall