pr-status: expose the release plan as a structured output #690

pr-status already computes the full release plan (via @changesets/get-release-plan) to build its comment, then only exposes comment-body. Could it also surface that same data as structured outputs?

These would be suuuper useful:

• max-bump: the highest of major/minor/patch across the released packages, or none
• releases: JSON array of { name, type, oldVersion, newVersion } per package

The current code for this action already carries all of this (per-package type plus old and new versions), so nothing new needs computing.

I currently label a PR patch/minor/major from the bump by manually parsing the files in the .changesets folder. The code for that would become much simpler if I could get these outputs directly. And this action already handles the pull_request_target fork-safety, so I wouldn't have to worry about that.

I already have a draft locally for this, but I wanted to check if this is something you'd be open to before I submit it. If so, I can clean it up and submit a PR. Pls lmk!