Chart repository URL that matches an existing Rancher ClusterRepo spec.url.

Supported schemes:

• https://charts.example/helm — classic Helm index repository
• http://charts.example/helm — same (HTTP)
• oci://registry.example/charts — OCI chart registry (Rancher Manager 2.9+)

If catalog cannot find the chart version, the step refreshes that ClusterRepo like the Rancher UI (sets spec.forceUpdate and waits) and retries once. The ClusterRepo must already exist in Rancher; the step does not create it. Registry credentials for private OCI hosts belong on the ClusterRepo in Rancher, not on this step.