fix: use auto-merge for sync PR to respect approval requirement

[designcode]

Summary

• Changes sync workflow to use --auto flag instead of immediate merge
• The sync PR is created and queued for auto-merge after approval
• Fixes the failed sync run where gh pr merge was blocked by the 1-approval requirement on main

Test plan

• After next stable release, verify sync PR is created with auto-merge enabled
• Approve the PR to trigger the merge

🤖 Generated with Claude Code

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Note

Low Risk
Low risk workflow-only change that alters how the sync PR is merged; main impact is operational (PRs now wait for required approvals before merging).

Overview
Updates the sync-release-to-main GitHub Actions workflow to enable auto-merge for the release-to-main sync PR instead of merging immediately.

The gh pr merge invocation now uses --auto, so the sync PR is queued and merges only after branch protection requirements (e.g., required approvals) are satisfied.

^{Reviewed by Cursor Bugbot for commit 8d9cd7f. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

🎉 This PR is included in version 2.17.0 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

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