Add rstream operator

[uartnet]

BACKGROUND

Add rstream operator as a Kubernetes 1-Click App. The integration installs the existing upstream Helm chart directly from its public OCI package and does not copy or vendor the chart.

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Changes

• add deploy, upgrade, and uninstall scripts for rstream operator
• pin the existing OCI Helm chart to version 0.5.2
• add the stack values file expected by the Marketplace
• preserve Helm-managed CRDs during uninstall to avoid deleting user resources

The submitted chart version passes anonymous OCI pull, Helm rendering with the submitted values, shell syntax, and ShellCheck validation. The deployment lifecycle was also tested on a clean local Kubernetes 1.36 cluster using the preceding chart version: deploy completed with the controller Ready, upgrade created a successful second Helm revision, and uninstall removed the release and namespace.

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Checklist

• Reviewed the contributing document and followed the required add-application steps.

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Reviewer: @marketplace-eng

[uartnet]

Refreshed the submission to use the existing rstream-operator OCI chart v0.5.2. The chart metadata, Helm rendering with the submitted values, deployment script syntax, and ShellCheck validation pass locally.