feat(deploy): add helm and openshift support

[brtydse100]

Summary

• add a starter single-image Helm chart under deployment/helm/docs-mcp-server
• support PVCs, existing claims, ephemeral storage, optional Ingress/OpenShift Route, and templated extraResources
• make the production image compatible with arbitrary non-root UIDs in group 0 and document mounted-volume ownership requirements
• extend Docker E2E and CI with arbitrary-UID and local-cluster Helm coverage

Verification

• production Docker build succeeds with Node.js 22

pm run test:docker: 8/8 passed, including Chromium, native PDF processing, HTTP startup, arbitrary UID 1000710000, and inaccessible-volume failure

• Helm lint/render matrix and Kubernetes server-side dry runs pass
• kind install, rollout, helm test, PVC writes, persistence after pod replacement, and arbitrary-UID deployment pass
• Node.js 22 typecheck and build pass
• scoped pre-commit lint/format hook passes
• standard suite: 2321/2325 passed in the disposable Linux harness; four concurrent E2E cases timed out while triggering a first-run Playwright browser download (the dedicated production-image Playwright test passes)