Add a check on the release PRs to verify (via AI) that all documentation is accurate and up-to-date with the proposed release

[jwilger]

Is your feature request related to a problem? Please describe.
When someone is using the library, if the documentation is outdated, then they are not able to use it effectively without a lot of friction. They may even give up on the library entirely.

Describe the solution you'd like
When a release PR is created in GH Actions, there should be a check that verifies all of our user-facing (i.e. developers using eventcore and/or implementing backends) documentation is accurate and up-to-date for the state of the library in the proposed release. If there are any changes needed, it should open a new PR to main with the proposed changes and fail the check. This could be implemented as a claude code review, replacing the normal review that happens on regular PRs (which we currently skip on release PRs).

Describe alternatives you've considered

• just remembering to do it (people won't)
• doing it as part of every PR (sometimes the API is in flux before a release, and that would be wasted effort)