[nschonni]

Description

Includes changes from #2678 used to support the Alpha concept.

Motivation and Context

Testing Details

1. Download the current stackbrew output from https://raw.githubusercontent.com/docker-library/official-images/refs/heads/master/library/node locally. I called mine stackbrew in the root of the folder
2. Stage the downloaded file
3. Run ./stackbrew.mjs stackbrew and compare the diff with the staged change. The first line should be changed, and there may be a blank line change at the end

Example Output(if appropriate)

Types of changes

• Documentation
• Version change (Update, remove or add more Node.js versions)
• Variant change (Update, remove or add more variants, or versions of variants)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Other (none of the above)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING.md document.
• All new and existing tests passed.

[nschonni]

note sure if some of the other combos of floating variants should also be added like:

• alpha for the default Debian
• alpha-slim for the default Debian-slim
• alpha-alpine for whatever is the default Alpine during the Alpha
  Could skip the various alpha-trixie, etc though