give segmentation QA the same threshold-independent view as detection

Detection QA reports a precision/recall curve, average precision and a
calibration sweep; segmentation QA reported a single operating point. Both rank
their outputs by confidence, so the same view applies, and the asymmetry meant
the two panels answered different questions about comparable runs — an
inconsistency introduced when detection gained the curve.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/app/api/routes/segmentation.py

@@ -223,5 +223,6 @@ def compare_segmentation_run_with_reference(
             iou_threshold=payload.iou_threshold,
             class_name=payload.class_name,
             min_confidence=payload.min_confidence,
+            calibration_thresholds=payload.calibration_thresholds,
         )
     )