fix: update multus HelmRelease to use chartRef for OCIRepository

Changed from chart.spec.sourceRef to chartRef to match the correct
format used by other working HelmReleases with OCIRepository sources.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: carpenike

kubernetes/cluster-0/apps/network/multus/app/helmrelease.yaml

@@ -6,14 +6,10 @@ metadata:
   name: multus
 spec:
   interval: 30m
-  chart:
-    spec:
-      chart: app-template
-      version: 4.0.1
-      sourceRef:
-        kind: OCIRepository
-        name: app-template
-        namespace: flux-system
+  chartRef:
+    kind: OCIRepository
+    name: app-template
+    namespace: flux-system
 
   values:
     controllers: