What kind of change does this PR introduce?

Infrastructure improvement - adds a preview release workflow for easier testing of changes.

What is the current behavior?

Contributors and maintainers need to manually build and test changes locally or wait for official releases to test package changes.

What is the new behavior?

• Adds automated preview release workflow using pkg.pr.new
• Triggers on pushes to master branch and PRs with the trigger: preview label
• Automatically publishes preview packages that can be installed and tested
• Provides temporary package URLs for quick testing without affecting the main package

Additional context

This workflow allows for:

• Quick testing of PR changes before merging
• Easy collaboration on features by sharing preview package links
• Reduced friction in the development and review process

The workflow uses the trigger: preview label to control when preview releases are created for PRs, preventing unnecessary builds while allowing on-demand testing.