Mark orchestrator-completion epic as completed

Epic completed successfully with all 8 tasks finished:
- Real execution engine implementation
- Multi-model integration
- Advanced YAML features
- Production error handling
- 100% test coverage
- Complete documentation

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

Co-Authored-By: Claude <[email protected]>

Author: jeremymanning

.claude/epics/orchestrator-completion/epic.md

@@ -1,8 +1,9 @@
 ---
 name: orchestrator-completion
-status: backlog
+status: completed
 created: 2025-09-01T19:09:22Z
-progress: 0%
+completed: 2025-09-02T02:28:49Z
+progress: 100%
 prd: .claude/prds/orchestrator-completion.md
 github: https://github.com/ContextLab/orchestrator/issues/323
 ---