Refactor UnifiedCoordinator to follow Single Responsibility Principle

- Create dedicated service classes for separated concerns:
  * AgentService: Agent management and health monitoring
  * WorkflowService: Workflow parsing and execution tracking
  * PerformanceService: Metrics and load balancing
  * BackgroundService: Background processes and cleanup
  * TaskService: Database persistence (already existed)

- Refactor UnifiedCoordinator into UnifiedCoordinatorRefactored
  * Clean separation of responsibilities
  * Improved maintainability and testability
  * Dependency injection pattern for services
  * Clear service boundaries and interfaces

- Maintain backward compatibility through re-exports
- Update main.py to use refactored coordinator

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

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

backend/app/main.py

@@ -9,7 +9,7 @@ from datetime import datetime
 from pathlib import Path
 import socketio
 
-from .core.unified_coordinator import UnifiedCoordinator
+from .core.unified_coordinator_refactored import UnifiedCoordinatorRefactored as UnifiedCoordinator
 from .core.database import engine, get_db, init_database_with_retry, test_database_connection
 from .api import agents, workflows, executions, monitoring, projects, tasks, cluster, distributed_workflows, cli_agents, auth
 from .models.user import Base