feat(rewards): add reset_scorer() stub for novelty scorer reset between episodes

rewards/compute_rewards.py

@@ -8,3 +8,7 @@ def compute_rewards(action: Any, attack_history: list[dict], llm_result: dict) -
         "feedback":      "Stub reward feedback.",
         "safety_flagged": False,
     }
+
+def reset_scorer() -> None:
+    """Reset Person 2's novelty embeddings."""
+    pass