Use workflow result for commit style

[MikeMcQuaid]

Needs Homebrew/actions#905

• Drop the status write that fork pull requests cannot receive.
• Pin the action version for now that fails the workflow on validation errors.
• Report the required check for synthetic merge queue commits.

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OpenAI GPT 5.6 sol xhigh with local review.

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[Copilot]

Pull request overview

Updates the Commit Style GitHub Actions workflow to rely on the workflow/job result as the required check (instead of writing commit statuses), and to run for merge queue (“merge_group”) events so synthetic merge commits still receive the required check result.

Changes:

• Add merge_group as a trigger so the workflow runs for merge-queue commits.
• Remove statuses: write permission and stop passing an explicit token to avoid status writes that fork PRs can’t receive.
• Pin Homebrew/actions/check-commit-format to a specific commit SHA (updated pin).

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