Pull request overview

This PR attempts to deflake the broken links check in the documentation workflow by splitting the build and test steps, restricting YARD generation to pull requests only, and adding a fallback mechanism for YARD failures.

Changes:

• Split the combined "Build the site without YARD and check for broken links" step into two separate steps for easier debugging and potential retry
• Restrict YARD documentation generation to only run on pull requests (not push or merge_group events)
• Add fallback logic to build without YARD if YARD generation fails

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.