feat: 实现 AgentScope ReAct Runner 两阶段执行并重构事件处理

backend/tests/unit/core/agentscope/events/test_pipeline.py

@@ -17,12 +17,13 @@ async def test_pipeline_orders_codec_persist_publish() -> None:
     class _Store:
         async def persist(self, event: dict[str, object]) -> None:
             calls.append("persist")
-            assert event["type"] == "RUN_STARTED"
+            assert event["id"] == "evt-1"
 
     class _Bus:
         async def publish(self, *, session_id: str, event: dict[str, object]) -> str:
             calls.append("publish")
             assert session_id == "thread-1"
+            assert event["type"] == "RUN_STARTED"
             return "1-0"
 
     pipeline = AgentScopeEventPipeline(codec=_Codec(), store=_Store(), bus=_Bus())