[Feature] CI Checks for Stale PRs

[theap06]

Summary

There are many stale and old PRs right now. I'd like to help cut down maintenance load: a lot of PRs seem to stall on slow/flaky CI. Would you be open to me taking some of that on? I was thinking of starting small with a lightweight CI check that catches public-API/import/doc breakages automatically (the kind of thing that's easy to miss in review), and then looking into flaky-test triage. Happy to scope it to whatever's most useful to you.

[vmoens]

sure but IMO many stall PRs are more stall because of lack of time to finalize the work / properly review the changes - more than because of failing tests. That being said catching issues in the CI better is definitely a good thing to have.
We should also work on making tests run faster. Agents add a ton of tests, sometimes expensive ones. Pytest prints our the most expensive tests at the end of the run, that is the first place to look at. Next we could consider breaking out tests better such that tests are scoped for the features that are modified.