feat(review): add Git change review tabs

[JairEsk]

Summary

• add a Changes chip that opens a dedicated Git review tab in the browser window
• support unstaged, staged, branch, and commit scopes with lazy per-file diffs
• add stage, unstage, and confirmed revert actions, including rename and unborn-repository handling
• support multi-repo sessions across file lists, commits, and bulk operations
• centralize shared review types and polling/layout constants, with no inline SVG assets
• normalize CRLF diffs and safely skip binary, oversized, and escaping paths

Testing

• npm run build
• npm run smoke
• npm run smoke:review (49 checks)
• Prettier and git diff --check