- Health status dot (green/yellow/red/gray) from worst-case check state
- Relative 'last seen' with color-coded staleness thresholds
- Response time badge from latest monitoring check
- Subscriber count badge from Gaiia inventory items
- Batch queries to avoid N+1: Monitoring.get_device_health_summary/1,
Monitoring.get_device_latest_response_times/1,
Gaiia.get_device_subscriber_counts/1
