Evaluation: Display overall score summary

Is your feature request related to a problem?
v2 runs include score.overall and an ai_summary for identifying the weakest questions, but these are not displayed on the run detail page. This makes it difficult for users to quickly assess the overall performance of their runs.

Describe the solution you'd like

• Display score.overall at the top of the run detail page, including overall_score, verdict, and breakdown (score, weight, delta, verdict)
• Show ai_summary as a diagnostic note above the per-row table
• Ensure graceful degradation when ai_summary is null or when overall is absent on v1 runs

从运行详情页面开始，检查当前如何呈现 v1 和 v2 的运行数据，尤其是分数字段。完成的标准是：页面显示总体分数及明细，在 AI 摘要可用时显示该摘要，并且在摘要为 null 或总体数据缺失时仍可正常使用。