test: 更新 AgentScope 相关单元测试与集成测试

- 重命名 test_react_runner.py 为 test_runner.py
- 新增 test_utils.py 测试工具函数
- 更新现有测试用例适配新架构

backend/tests/integration/v1/agent/test_routes.py

@@ -64,14 +64,11 @@ class _FakeAgentService:
     ) -> dict[str, object]:
         del current_user, before
         return {
-            "type": "STATE_SNAPSHOT",
             "threadId": thread_id or "00000000-0000-0000-0000-000000000001",
-            "snapshot": {
-                "scope": "history_day",
-                "day": "2026-03-07",
-                "hasMore": False,
-                "messages": [],
-            },
+            "scope": "history_day",
+            "day": "2026-03-07",
+            "hasMore": False,
+            "messages": [],
         }
 
     async def upload_attachment(
@@ -277,10 +274,9 @@ def test_history_returns_state_snapshot() -> None:
         )
         assert authorized.status_code == 200
         payload = authorized.json()
-        assert payload["type"] == "STATE_SNAPSHOT"
+        assert payload["scope"] == "history_day"
         assert payload["threadId"] == "00000000-0000-0000-0000-000000000001"
-        assert payload["snapshot"]["scope"] == "history_day"
-        assert payload["snapshot"]["day"] == "2026-03-07"
+        assert payload["day"] == "2026-03-07"
     finally:
         app.dependency_overrides = {}
 
@@ -295,7 +291,7 @@ def test_user_history_returns_latest_snapshot() -> None:
         response = client.get("/api/v1/agent/history")
         assert response.status_code == 200
         body = response.json()
-        assert body["type"] == "STATE_SNAPSHOT"
+        assert body["scope"] == "history_day"
         assert body["threadId"] == "00000000-0000-0000-0000-000000000001"
     finally:
         app.dependency_overrides = {}