feat(iace): add distance dimension to GT benchmark

CompareBenchmark now also compares the engine's numeric dimensions
(mm gaps, mm/s speeds) against the professional's GT measures: parses
distance tokens from both sides (German thousands/decimal aware),
reports matched / gt_only (gaps) / engine_only + an agreement %.
Surfaces as result.distances on the existing benchmark endpoint.

Deterministic, no LLM. On the GT-derived seed sessions it mainly guards
DRIFT; its real value is new sessions. Real-GT test pins that the engine
covers the Bremse (250 mm/s, 250/850 mm) and Kistenhub (25/120 mm,
150/75 mm/s) headline dimensions.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ai-compliance-sdk/internal/iace/benchmark_matcher.go

@@ -149,6 +149,8 @@ func CompareBenchmark(gt *GroundTruth, hazards []Hazard, mitigations []Mitigatio
 		coverage = float64(len(matched)) / float64(len(gt.Entries))
 	}
 
+	dist := CompareSessionDistances(gt, mitigations)
+
 	return &BenchmarkResult{
 		CoverageScore:     coverage,
 		MeasureCoverage:   measCov,
@@ -159,6 +161,7 @@ func CompareBenchmark(gt *GroundTruth, hazards []Hazard, mitigations []Mitigatio
 		ExtraInEngine:     extra,
 		CategoryBreakdown: breakdown,
 		RiskRankPairs:     rankPairs,
+		Distances:         &dist,
 	}
 }
 
@@ -439,9 +442,9 @@ func buildRiskRankPairs(matched []HazardMatchPair) []RiskRankPair {
 
 	// Sort by GT risk descending to get GT rank
 	type ranked struct {
-		idx     int
-		gtRisk  int
-		name    string
+		idx    int
+		gtRisk int
+		name   string
 	}
 	items := make([]ranked, len(matched))
 	for i, m := range matched {