k8s/monitoring: add prometheus grafana loki observability

- Loki log aggregation (MinIO backed, 10-day retention)
- Promtail daemonset (pod + talos journal logs)
- Prometheus + kube-state-metrics
- Grafana dashboards (6-row template per service)

k8s/monitoring/servicemonitors/minio.yaml

@@ -0,0 +1,19 @@
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: minio
+  namespace: monitoring
+  labels:
+    release: kube-prometheus-stack
+spec:
+  namespaceSelector:
+    matchNames:
+      - storage
+  selector:
+    matchLabels:
+      app: minio
+  endpoints:
+    - port: minio-api
+      path: /minio/v2/metrics/cluster
+      interval: 30s
+      scrapeTimeout: 10s