Request PR write permission for guidance comments

[trask]

Request Pull requests write permission when minting the dashboard app token for the review-guidance job, matching the updated GitHub App permission. Update the webhook setup docs to document that PR conversation guidance comments require Pull requests read and write access.

[Copilot]

Pull request overview

This PR aligns the post-review-guidance job's GitHub App token with the permissions actually required to post PR conversation guidance comments. The post-review-guidance job uses a minted GitHub App installation token to read existing PR comments and post a guidance comment via the issues comments REST endpoint. For GitHub App tokens, commenting on a pull request through that endpoint requires pull_requests: write (not just issues: write), so the prior read scope would fail. The documentation is updated to reflect this requirement.

Changes:

• Upgrade permission-pull-requests from read to write for the post-review-guidance token.
• Update WEBHOOK_SETUP.md to document that PR conversation guidance comments require Pull requests: read and write, including the permission table rows and rationale paragraph.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
.github/workflows/pull-request-dashboard-repo.yml	Grants the review-guidance app token pull_requests: write so it can post PR conversation comments.
.github/scripts/pull-request-dashboard/WEBHOOK_SETUP.md	Updates the App permission list, rationale table, and summary to state that posting guidance comments needs Pull requests: read and write.

---

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