Restore the cluster deployment layer (releases, contexts, flux) under clusters/sandbox

[jpmewenemesse]

Problem Statement

After the package/chart migration, okdp-sandbox was reduced to documentation only. The goal is to re-scope the two repos:

• okdp-sandbox: cluster deployment only. Its purpose will be to consume published packages

Proposed Solution

The proposed solution is

• To bring the deployment layer back into okdp-sandbox, reusing the improved namings introduced in platform-packages (split contexts, releases/ instead of releases/addons)
• Update documentation as deployment guide

Acceptance criteria

• clusters/sandbox/{flux,release,contexts} populated with the new namings from platform-packages
• kubocd/flux reconcilies against the packages
• All releases resolve and deploy on a sandbox cluster
• README+ docs describe the deployment only scope

Alternatives Considered

No response

Additional Context

No response