Summary

• Add verification after gh pr merge --squash --auto to confirm merge was actually enabled (check state == MERGED or autoMergeRequest != null)
• Add 10s sleep + one retry when first check fails, to handle transient GitHub mergeStateStatus: UNKNOWN state right after CI completes
• Fall back to bot:ready-to-merge with a comment if both attempts fail, instead of silently labeling bot:done

Test plan

• Trigger pr-automation on a PR with all CI passing — verify it merges and labels bot:done
• Simulate transient failure: verify retry after 10s succeeds
• Simulate persistent failure: verify PR is labeled bot:ready-to-merge with a comment