Switch stale-issues to stale-issues-investigator

[strawgate]

Summary

• Replaces gh-aw-stale-issues.lock.yml with gh-aw-stale-issues-investigator.lock.yml
• The investigator actively examines open issues for evidence of resolution (linked PRs, code changes, conversation consensus) rather than just checking activity dates
• Labels identified candidates as stale and files a summary report issue
• Removes the additional-instructions workaround about not having permission to close issues — the investigator labels and reports instead of attempting to close
• Drops the unused actions: read permission

Made with Cursor

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b add-basic-triage-workflows upstream/add-basic-triage-workflows
git merge upstream/main
git push upstream add-basic-triage-workflows

[mergify]

This pull request does not have a backport label. Could you fix it @strawgate? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-./d./d is the label that automatically backports to the 8./d branch. /d is the digit
• backport-active-all is the label that automatically backports to all active branches.
• backport-active-8 is the label that automatically backports to all active minor branches for the 8 major.
• backport-active-9 is the label that automatically backports to all active minor branches for the 9 major.