feat(monitoring): add health checks and alert rules for observability stack

- Add comprehensive health checks to all monitoring services (Prometheus, Grafana, Loki, Tempo, Promtail, node-exporter, celery-exporter)
- Create Grafana alert rule configuration for CPU usage monitoring
- Implement logging configuration with rotation limits for Loki, Tempo, and Promtail
- Document post-upgrade fixes and health status in detailed reports

Author: welshDog