Update all ArgoCD Application references to use Gitea (github0213.com) instead of GitHub for K3S-HOME/observability repository. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- Add blackbox-exporter with prometheus-community Helm chart - Configure HTTP probes for 25 external endpoints - Include SSL certificate expiry alerting rules - Add probe failure and slow response alerts - Deploy 2 replicas with anti-affinity for HA
