feat: side panel shows per-juror baseline and balanced contribution

Extends the ranking router's roundEvaluationScores response with
per-juror grading stats (mean, stddev, count) plus the round's overall
mean/stddev. The side-sheet juror rows render 'typical X.XX →
contributes Y.YY' next to each Score badge whenever balanced is on,
making the z-rescaling visible per individual rather than only as a
project-level number.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/admin/round/ranking-dashboard.tsx

@@ -1136,6 +1136,28 @@ export function RankingDashboard({ competitionId: _competitionId, roundId }: Ran
                                   </Badge>
                                 )}
                                 <Badge variant="outline">Score: {a.evaluation?.globalScore?.toFixed(1) ?? '—'}</Badge>
+                                {useBalanced && (() => {
+                                  const userId = a.user?.id
+                                  const score = a.evaluation?.globalScore
+                                  if (!userId || score == null) return null
+                                  const stats = evalScores?.jurorStats?.[userId]
+                                  const overallMean = evalScores?.overallMean
+                                  const overallStddev = evalScores?.overallStddev
+                                  if (!stats || overallMean == null || overallStddev == null || overallStddev === 0) return null
+                                  const z = stats.stddev > 0
+                                    ? (score - stats.mean) / stats.stddev
+                                    : (score - overallMean) / overallStddev
+                                  const contributesAs = overallMean + z * overallStddev
+                                  return (
+                                    <span
+                                      className="text-xs text-muted-foreground"
+                                      title={`Their typical score in this round; rescaled contribution after juror balancing`}
+                                      onClick={(e) => e.stopPropagation()}
+                                    >
+                                      typical {stats.mean.toFixed(2)} → contributes {contributesAs.toFixed(2)}
+                                    </span>
+                                  )
+                                })()}
                               </div>
                             </div>
                             {isExpanded && a.evaluation?.feedbackText && (