Clarify primary inference configuration

pipeline_config.json

@@ -16,8 +16,18 @@
   "primary_score": "95th percentile of spatial anomaly map",
   "provisional_threshold": 0.7,
   "threshold_status": "exploratory; not validated on held-out data",
-  "classifier_artifact": "parcelguard_image_classifier.joblib",
   "backbone_artifact": "parcelguard_resnet18_layer2.pt",
   "inference_module": "src/predict.py",
-  "status": "experimental"
-}
+  "status": "experimental",
+  "experimental_classifier_artifacts": [
+    "parcelguard_baseline.joblib",
+    "parcelguard_image_classifier.joblib"
+  ],
+  "primary_inference": {
+    "module": "src/predict.py",
+    "required_artifact": "parcelguard_resnet18_layer2.pt",
+    "scoring": "P95 of the spatial anomaly map",
+    "threshold": 0.7,
+    "threshold_status": "exploratory; not validated on held-out data"
+  }
+}