feat(frontend): add Helm chart browser, monitoring, chart-references and values templates pages

Add new frontend pages for the multi-tenant OCDP platform:

- Charts page (/charts): Browse Harbor OCI registries to list Helm chart repositories
  and versions, with deploy modal to launch charts on selected clusters
- Monitoring page (/monitoring): Display cluster metrics (CPU/Memory/GPU usage)
  and per-node details with resource utilization bars
- Chart References page (/chart-references): CRUD for chart metadata references
- Values Templates page (/templates): CRUD for Helm values templates with version
  history and rollback support
- Sidebar: Add Charts navigation, update Storage and Templates links
- api.ts: Add all API client functions (clusterApi, registryApi, instanceApi,
  monitoringApi, storageApi, chartReferenceApi, valuesTemplateApi,
  workspaceApi, userApi) with full TypeScript types

Note: deploy flow and values template rollback not yet end-to-end tested.

backend/docker-compose.yml

@@ -67,6 +67,13 @@ services:
       JWT_SECRET: ${JWT_SECRET:-change-me-in-production}
       ENCRYPTION_KEY: ${ENCRYPTION_KEY:-change-me-32-bytes-long-key-here}
       DATABASE_URL: postgresql://${POSTGRES_USER:-postgres}:${POSTGRES_PASSWORD:-postgres}@postgres:5432/${POSTGRES_DB:-ocdp}?sslmode=disable
+      KUBECONFIG: ${KUBECONFIG:-.kube/config}
+      HARBOR_URL: ${HARBOR_URL:-}
+      HARBOR_USERNAME: ${HARBOR_USERNAME:-}
+      HARBOR_PASSWORD: ${HARBOR_PASSWORD:-}
+      NFS_SERVER: ${NFS_SERVER:-}
+      NFS_SHARE: ${NFS_SHARE:-}
+      ALLOWED_DEV_ORIGINS: ${ALLOWED_DEV_ORIGINS:-}
     ports:
       - "${BACKEND_PORT:-8080}:8080"
     volumes: