HF upload pipeline: include Q1-Q8 matrix records and publish summary

[ShuhaoZhangTony]

Task

Extend current HF upload flow to better surface matrix coverage.

Requirements

• Keep existing merge safety semantics
• Upload Q1~Q8 records once generated
• Add post-merge coverage summary (counts by workload/backend/seed)
• Fail if malformed records are detected

Acceptance Criteria

• benchmark_results.json includes q1..q8 entries after matrix run
• Workflow logs show per-workload record counts
• No duplicate explosion for repeated runs

[ShuhaoZhangTony]

软件侧修复已提交至 #28：HF workflow 从已删除的 main-dev 改为现存 main，使用官方写入端点，聚合阶段输出 workload/backend/seed coverage summary，并上传 summary 与结果文件。

本 Issue 仍需要仓库维护者确认 HF_TOKEN，再用真实 Q1–Q8 数据完成一次上传并核对数据集内容；在这组外部发布证据出现前不能关闭。

我已移除 PI 占位 assignee 并标记 help wanted。