🛠 Tooling: a11y and compliance bots aren't posting on PRs from forks

[JoshuaKGoldberg]

Bug Report Checklist

• I have tried restarting my IDE and the issue persists.
• I have pulled the latest main branch of the repository.
• I have searched for related issues and found none that matched my issue.

Overview

As seen in #374, this is the classic permissions issue with those bots where they don't have permissions to post comments:

• 🐛 Bug: No fallback behavior for action runs on forks github/accessibility-alt-text-bot#44
• Give a better error than "Resource not accessible by integration" when permissions lacking mtfoley/pr-compliance-action#368

In my other repos I've switched to OctoGuide (disclaimer: I also wrote that thing). Its reporting is a bit more resilient in general. So I'm thinking we could/should just move to OctoGuide here and reduce the number of CI things?

Additional Info

Example other OctoGuide usage: https://github.com/SquiggleTools/SquiggleConf.com/blob/dfb9e277ba5984b528c22a98d9c8c6223bed6fd1/.github/workflows/octoguide.yml

I also wonder if we should remove the "associated issue" check as part of this. It's not really relevant here...