refactor(git): delegate git:review to peer orchestrator

[ppzxc]

What to build

Refactor plugins/git/skills/review/SKILL.md to delegate its cross-review and orchestration steps to the llm:peer-orchestrator skill, simplifying the git:review skill.

Acceptance criteria

• Redundant review orchestration steps are removed from git:review.
• Running /git:review successfully delegates to llm:peer-orchestrator and runs PR code review and auto-fix logic normally.

Blocked by

• refactor(llm): delegate llm:auto to peer orchestrator #134