Evaluation: Categorize scores with labels #1071

Is your feature request related to a problem?
Eval scores are currently presented as raw 0–1 floats without categorical labels in the data. This makes it difficult for API consumers to interpret scores as low/good/high without implementing their own thresholds, which the team agreed should be included in the data payload.

Describe the solution you'd like

• Define traffic-light buckets that map score to category label (e.g. low / good / high) for all judge metrics.
• Include the category label in the eval results data payload.
• Use a consistent scale (0–1) across all judge metrics.
• Future UI updates to color-code metric cards red/orange/green with an info button for recommendations.