OpenViking application.yaml: fix invalid Helm chart source (chart -> path)

- Changed source 1 from 'chart: deploy/helm/openviking' to 'path: deploy/helm/openviking'
- ArgoCD multi-source now correctly resolves the Helm chart from the git repo
- targetRevision: main now correctly refers to a git branch, not a chart version
- Fixes: invalid revision 'main': improper constraint error

cluster/platform/openviking/application.yaml

@@ -29,8 +29,8 @@ spec:
   sources:
     # Source 1: Helm chart from upstream VolcEngine/OpenViking repository
     - repoURL: https://github.com/volcengine/openviking.git
-      chart: deploy/helm/openviking
       targetRevision: main
+      path: deploy/helm/openviking
       helm:
         valueFiles:
           # Local values override upstream defaults