Creates a GitHub Action that triggers when CI completes for PRs with the
cc:request label. It runs /dyad:pr-fix to address failing checks and
review comments, then updates labels (removes cc:help, adds
cc:responded)

#skip-bugbot

<!-- This is an auto-generated description by cubic. -->
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## Summary by cubic
Adds a GitHub Action that auto-responds to PRs after CI completes. It
runs /dyad:pr-fix on PRs labeled cc:request from wwwillchen and updates
labels based on status.

- **New Features**
  - Triggers on CI workflow_run completion.
  - Checks out the PR’s head repo/branch and runs /dyad:pr-fix.
  - Restricts usage to PRs authored by wwwillchen.
- Updates labels: cc:request → cc:pending; then cc:done on success or
cc:failed on failure.
  - Uses write permissions for contents and pull-requests.

<sup>Written for commit 21cef82a88b2e3d591f4c3955b679dd28aad0477.
Summary will update on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

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Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>