Proactively address GitHub rate limit restrictions

A GitHub Copilot action shouldn't ever be set up to allow for rate limiting to come into effect:

`Sorry, you've hit a rate limit that restricts the number of Copilot model requests you can make within a specific time period. Please try again in 2 hours. Please review our Terms of Service (https://docs.github.com/site-policy/github-terms/github-terms-of-service). If the problem persists, please contact GitHub Support, including the request ID `3C32:203416:1304F41:153BE2E:698F2D51`. To retry, leave a comment on this pull request asking Copilot to try again.`

I'm seeing it here:
https://github.com/mgifford/o-hat-scanner/pull/26

It would probably be better if there were only 2 issues added per half hour, rather than having a bunch of new PRs created all at once.

This should be working within the resource limits of GitHub.

I don't know what I'm supposed to do with this:
https://github.com/mgifford/o-hat-scanner/actions/runs/21989364482/job/63531926200

Start by inspecting the GitHub Actions job at the linked run and the workflow that created the pull request at o-hat-scanner#26. Reproduce the burst of Copilot requests and determine how to enforce the proposed limit of two issues per half hour; done means the workflow stays within GitHub resource limits without triggering rate-limit failures.

Written by the indexing model from the issue text.