* chore(dockerfile): improve package installation and add Python dependencies
* chore(dockerfile): update package installation commands for consistency
* chore: update release version to dsh-v0.2.1-rc.5-r6 across documentation and configuration files
Remove obsolete layout/migration prose and legacy gateway-alias references, reconcile the required-check policy, fix version-label/RBAC/workspace/channel drift, and de-duplicate the example and gateway docs.
Rename the minimal manifest to 10-sandboxtemplate.yaml and mount the dsh-home PVC's workspace subPath at /workspace so the documented persistence is real. Enforce numbered top-level manifests in check-examples.sh.
Verified with make check, yamllint, shellcheck, a Markdown link/anchor scan, and git diff --check.
Co-authored-by: SREDevOpsAgents <agents@sredevops.org>
