feat(v2): add fall event regression engine

v2/internal/spike/ort_test.go

@@ -14,3 +14,13 @@ func TestRunPoseRejectsWrongInputLengthBeforeLoadingRuntime(t *testing.T) {
 		t.Fatalf("RunPose error = %q, want input length error", err)
 	}
 }
+
+func TestOpenRuntimeReportsMissingDLL(t *testing.T) {
+	_, err := OpenRuntime("missing.onnx", "missing.dll")
+	if err == nil {
+		t.Fatal("OpenRuntime accepted a missing ONNX Runtime DLL")
+	}
+	if !strings.Contains(err.Error(), "initialize ONNX Runtime") {
+		t.Fatalf("OpenRuntime error = %q", err)
+	}
+}