[2.15.0] Add /xcode-test command for iOS simulator testing

- New `/xcode-test` command for building and testing iOS apps
- Uses XcodeBuildMCP to discover projects, build, install, launch
- Takes screenshots and captures console logs
- Supports human verification for Sign in with Apple, push, IAP
- Checks for XcodeBuildMCP installation before proceeding

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

plugins/compound-engineering/README.md

@@ -7,7 +7,7 @@ AI-powered development tools that get smarter with every use. Make each unit of
 | Component | Count |
 |-----------|-------|
 | Agents | 27 |
-| Commands | 18 |
+| Commands | 19 |
 | Skills | 13 |
 | MCP Servers | 2 |
 
@@ -96,6 +96,7 @@ Core workflow commands use `workflows:` prefix to avoid collisions with built-in
 | `/resolve_todo_parallel` | Resolve todos in parallel |
 | `/triage` | Triage and prioritize issues |
 | `/playwright-test` | Run browser tests on PR-affected pages |
+| `/xcode-test` | Build and test iOS apps on simulator |
 
 ## Skills