- Add BranchManager.listCommits() and diffCommit() for commit-level navigation
- Add getPhaseReviewCommits and getCommitDiff tRPC procedures
- New ReviewHeader: consolidated toolbar with phase selector pills, branch info,
stats, integrated preview controls, and approve/reject actions
- New CommitNav: horizontal commit strip with "All changes" + individual commits,
each showing hash, message, and change stats
- Slim down ReviewSidebar: file list only with dimming for out-of-scope files
when viewing a single commit
- ReviewTab orchestrates all pieces in a single bordered card layout
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