Documentation: TPCH/TPCC-style benchmark guide (single-node first)

[ShuhaoZhangTony]

Task

Document the new benchmark matrix flow clearly.

Requirements

• Where to run Q1~Q8 matrix
• Single-node baseline commands
• Expected output layout and fields
• How to aggregate + upload to HF
• Troubleshooting section (missing deps, partial failures)

Acceptance Criteria

• README/docs have copy-paste command path
• New users can reproduce matrix run and upload end-to-end

[ShuhaoZhangTony]

完整单机指南已提交至 #28，覆盖可复制命令、输出目录与字段、失败策略、聚合/HF 发布、Actions 触发方式和常见故障排查。

本 Issue 由 #28 在合并后自动关闭；在 PR 合并前不提前宣称完成。