Improve image upload in debug drawer

backend/services/conversation_history.py

@@ -235,6 +235,9 @@ class ConversationRecorder:
                             },
                         )
                     )
+                    # Flush before artifact insert: db.get() below autoflushes and
+                    # can otherwise write conversation_artifacts first (FK violation).
+                    await db.flush()
                     db.add(
                         ConversationArtifact(
                             id=artifact_id,