Integrate releases and publish changelogs somewhere

It's hard to track changes and versions of the CLI at the moment. We do not have a github release to match each release. Npm doesn't list changelog notes for each version.

We've got beautiful tracking from changesets but we're not really publishing that information anywhere useful!

The complication with release notes is that each package has its own set of changes. Most of these impact the CLI, but the CLI itself may not have a useful changelog. For example, if I was to add a new security sandbox to the runtime, that CLI would gain that behaviour but wouldn't have its own diff. Thus you'd have a release note for runtime, but not for CLI.

I'd really like to show CLI changes like this:

# CLI 1.0.0

runtime: support workflows
compiler: ban classes
logger: allow to log json objects
logger: add new `trace` level

This style groups changes under the CLI, so that CLI users can easily see what's changed, but attributes them to the sub-package which they're implemented in.

So the work here is something like:

• Automatically create a github version for each release after merging to main
• Work out how to make the CLI changelog nicer
• Work out where to share the changelog (ideally we should be able to link to a single page with a nice clear listing of the versions and changes).

Also for the wishlist: migration guides and really clear breaking change notifications.

No files, tests, or entry points are named. Start by reviewing the existing changesets release flow and the merge-to-main process; done means releases produce GitHub versions and a clear CLI changelog that attributes package changes, with a defined place to publish it.