TKE-59: fix health check link findings

[wenjiehs]

Summary

• Fix broken cookbook README links to docs under src/content/docs.
• Replace stale supernode GPU best-practices URLs with the current supernode GPU page.
• Fix posts index routes to use generated site URLs.

Verification

• npm run build
• python3 -m py_compile cookbook/cluster/delete_cluster.py cookbook/cluster/create_cluster.py cookbook/cluster/describe_clusters.py cookbook/common/auth.py cookbook/common/logger.py cookbook/workload/deploy_nginx.py cookbook/supernode/deploy_gpu_pod.py
• git diff --check
• local sidebar/link/image scan

TKE-59

[github-actions]

✅ 构建成功！PR 合并后将自动部署。