Include branch name in review submission payload

[lovestaco]

The diff-review submission never sent the current git branch name to LiveReview, so CLI-sourced reviews always showed "-" for Branch in the dashboard. Resolve HEAD's branch and include it in the request.

Summary

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Linked Issue

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Validation

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Checklist

• This PR fulfills an agreed issue.
• I kept the change narrow and scoped.
• I ran the most specific relevant validation and described it above.
• If I changed behavior, I called that out clearly in this PR.
• If I touched UI, I attached a GIF or video walkthrough. This is required.
• If I changed storage/ responsibilities, I updated storage/storage_status.md and ran make check-status-doc.
• If I changed network/ responsibilities, I updated network/network_status.md and ran make check-status-doc.
• If this change touches security, disclosure flow, credentials, storage, network behavior, or remote data handling, I reviewed SECURITY.md and updated related documentation if needed.

Notes For Reviewers

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