feat(iace): benchmark risk comparison (traffic lights) + misuse pattern + 1:n matcher

#1 Risk-number comparison in the benchmark: ComputeRiskComparison derives the
tool's S/F/W/P + Fine-Kinney per matched hazard and compares to the GT values;
exposed on the benchmark response and rendered in a new RiskComparison table
with GREEN/YELLOW/RED traffic lights on the risk number R (like the Excel),
plus per-axis within-1 agreement cards.

#2 Generic misuse pattern HP2103 "Personenbefoerderung auf Hebezeug" — gated to
lift-family machine types, fires for ANY lifting device (not machine-specific).

#3 Benchmark matcher is now 1:n — one broad engine hazard may cover several
fine-grained GT sub-scenarios (foot/hand/leg crush), so coverage reflects real
risk coverage rather than 1:1 wording matches.

Validated on BOTH ground truths (robot cell + lift): leakage 0, ghosts 0,
coverage held.

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

ai-compliance-sdk/internal/api/handlers/iace_handler_benchmark.go

@@ -105,6 +105,7 @@ func (h *IACEHandler) RunBenchmark(c *gin.Context) {
 	}
 
 	result := iace.CompareBenchmark(gt, hazards, mitigations)
+	result.RiskComparison, result.RiskAgreement = iace.ComputeRiskComparison(result.MatchedPairs)
 	c.JSON(http.StatusOK, result)
 }