fix(minio): correct operator chart repoURL and pin version — charts.min.io lacks operator chart, use [email protected]

The operator chart moved to https://operator.min.io/; https://charts.min.io/ only
ships the standalone minio chart, causing 'chart operator not found in index'.
Pin to 5.0.18 (v5.x schema matches minio-operator-values.yaml operator.image.tag v5.0.0);
targetRevision '*' was fragile. Unblocks minio-tenant (needs operator CRDs).

k8s/argocd/apps/10-storage-observability.yaml

@@ -11,9 +11,9 @@ metadata:
 spec:
   project: homelab
   sources:
-    - repoURL: https://charts.min.io/
+    - repoURL: https://operator.min.io/
       chart: operator
-      targetRevision: "*"
+      targetRevision: "5.0.18"
       helm:
         valueFiles:
           - $values/k8s/infrastructure/minio/minio-operator-values.yaml