add zip agent based code reviewer agent

plugins/compound-engineering/README.md

@@ -6,7 +6,7 @@ AI-powered development tools that get smarter with every use. Make each unit of
 
 | Component | Count |
 |-----------|-------|
-| Agents | 36 |
+| Agents | 37 |
 | Skills | 48 |
 | Commands | 7 |
 | MCP Servers | 1 |
@@ -38,6 +38,7 @@ Agents are organized into categories for easier discovery.
 | `security-reviewer` | Exploitable vulnerabilities with confidence calibration |
 | `testing-reviewer` | Test coverage gaps, weak assertions |
 | `tiangolo-fastapi-reviewer` | FastAPI code review from tiangolo's perspective |
+| `zip-agent-validator` | Pressure-test zip-agent review comments for validity |
 
 ### Document Review