Add grounded NPC interaction extractor

internal/modules/dnd/extract/npcinteractions/model_test.go

@@ -0,0 +1,18 @@
+package npcinteractions
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestExtractionResponsePreservesValidatorOwnedSemantics(t *testing.T) {
+	content := []byte(`{"interactions":[{"name":"","kind":"unsupported","source_refs":[{"start_unit_id":0,"end_unit_id":-1}]}]}`)
+	var response extractionResponse
+	if err := json.Unmarshal(content, &response); err != nil {
+		t.Fatalf("json.Unmarshal() error = %v", err)
+	}
+	interaction := response.Interactions[0]
+	if interaction.Name != "" || interaction.Kind != "unsupported" || interaction.SourceRefs[0] != (interactionSourceRefResponse{StartUnitID: 0, EndUnitID: -1}) {
+		t.Fatalf("decoded response = %#v", interaction)
+	}
+}