Add celery monitoring endpoint

[paktusov]

Add Celery and RabbitMQ Monitoring Endpoints

This PR introduces monitoring capabilities for Celery workers and RabbitMQ queues, providing real-time insights into task processing and message queue status.

What's Changed

New Features:

• Celery Monitoring Endpoint (/api/monitoring/celery/)

  • Real-time monitoring of active, scheduled, and pending tasks
  • Worker-level task statistics and counts
  • Support for multiple worker types (workflow, backend, etc.)

• RabbitMQ Monitoring Endpoint (/api/monitoring/rabbitmq/)

  • Queue status monitoring for main application queues
  • Message counts and consumer utilization metrics
  • Grouped by queue types (workflow, backend)

Technical Implementation:

• New monitoring module (workflow/monitoring.py) with CeleryMonitoring and RabbitMQMonitoring classes
• API serializers for structured data responses
• ViewSets with proper error handling
• Comprehensive test suite with mocked dependencies

API Endpoints

GET /{realm_code}/{space_code}/workflow/api/monitoring/celery/
GET /{realm_code}/{space_code}/workflow/api/monitoring/rabbitmq/

Benefits

• Operational Visibility: Real-time monitoring of task processing
• Performance Insights: Queue utilization and consumer metrics
• Debugging Support: Detailed task and queue information
• System Health: Proactive monitoring capabilities

Testing

• All new tests pass
• Mocked external dependencies
• Error handling scenarios covered
• API consistency validated

Ticket: PLAT-1898
Type: Feature
Breaking Changes: None