Monitors the health of subscriptions and their associated emitter pools.

This module provides comprehensive health monitoring for the subscription system:

• Detects stale subscriptions (subscriber process is dead)
• Identifies orphaned emitter pools (pools without corresponding subscriptions)
• Finds missing emitter pools (subscriptions without pools on leader nodes)
• Automatically triggers cleanup and recovery actions
• Provides detailed health reports for observability

The monitor runs periodic health checks and can be triggered manually for immediate diagnostics.