feat: add counting bench, triage, and dataset modules

This commit includes major additions and updates to the frontend and backend architectures, introducing new dataset management, live counting features, batch processing, and triage logic. Includes new UI pages, components, and API routes.

backend/labeling.py

@@ -43,7 +43,11 @@ def _iou(box_a: List[float], box_b: List[float]) -> float:
 
 def deduplicate(detections: List[Detection], iou_threshold: float = 0.8) -> List[Detection]:
     """Greedy NMS per class: highest score wins within the SAME class."""
+    if iou_threshold <= 0.0:
+        return detections
+
     by_class: dict[int, List[Detection]] = {}
+
     for det in detections:
         by_class.setdefault(det.class_id, []).append(det)