GitHub Copilot Code Review: Custom Instructions from Feature Branch and Independent Firewall Configuration

What's new

• Instructions from feature branch: REVIEW.md, GEMINI.md, CLAUDE.md are now read from the feature branch, not the base — test review rules without merging first
• copilot-code-review.yml: New workflow file in .github/workflows/ for custom setup steps, dependencies, and environment config independent of the cloud agent
• Network firewall: Network access restrictions now run by default during reviews; Copilot Internet access setting decoupled from the cloud agent config
• Independent runner type: Runner type for code review and cloud agent is now independently configurable via Copilot Runner type setting

Why it matters

These changes remove the most common enterprise blockers for adopting Copilot code review at scale — branch-level rule testing without merging, and air-gapped review environments decoupled from cloud agent workflows.