Judge dashboard

The Judge page surfaces:

• Trailing 30-day mean composite with a 7-day moving average.
• Per-component breakdown of judge scores (which prompts struggle).
• Prompt-A/B status — every active candidate with its sample size, current win/loss vs. the active baseline, and confidence interval.
• Drift alerts — when the daily mean drops more than 0.10 from the trailing 7-day baseline.