feat(backend): 完善 Workflow 与 DeepResearch 的运行链路与持久化能力

功能说明：\n- 重构并增强工作流网关执行链路，支持更完整的 proposal 与 run 调度参数透传\n- 增加 DeepResearch/workflow 运行事件持久化能力并补齐建表 SQL 与查询/保存接口适配\n- 优化 lead agent 与 deep research runner 的中间态处理，增强线程收集与执行链并发控制\n- 调整工作流执行器与任务路由，提升兼容性并完善错误与回放行为\n- 补充回归测试：deep_research 持久化、workflow 并发、定义加载、引擎执行、run 流程等覆盖

offline-backend-20260512/backend/tests/test_workflow_engine.py

@@ -663,6 +663,60 @@ async def test_agent_node_streams_deltas_and_parses_json() -> None:
     }
 
 
+@pytest.mark.asyncio
+async def test_agent_clarification_pauses_and_resume_is_routed_to_the_same_node() -> None:
+    seen_resume_payloads: list[dict[str, Any] | None] = []
+
+    async def run_agent(**kwargs: Any) -> dict[str, Any]:
+        resume_payload = kwargs.get("resume_payload")
+        seen_resume_payloads.append(resume_payload)
+        if resume_payload is None:
+            return {
+                "awaiting_input": {
+                    "toolCallId": "clarify-1",
+                    "prompt": "请确认分析的地域范围。",
+                    "actions": ["submit"],
+                }
+            }
+        assert resume_payload["values"] == {"answer": "中国市场"}
+        return {"text": "已按中国市场范围完成分析。"}
+
+    graph = _graph(
+        [
+            {"id": "start", "type": "start"},
+            {
+                "id": "research",
+                "type": "agent",
+                "config": {"agentId": "researcher", "promptTemplate": "分析 {{ inputs.topic }}"},
+            },
+            {"id": "end", "type": "output", "config": {"mapping": {"text": "{{ nodes.research.data.text }}"}}},
+        ],
+        [
+            {"id": "e1", "source": "start", "target": "research"},
+            {"id": "e2", "source": "research", "target": "end"},
+        ],
+    )
+    deps = WorkflowRuntimeDeps(run_agent=run_agent)
+
+    with pytest.raises(WorkflowPaused) as paused:
+        await _run(graph, {"topic": "新能源车"}, deps=deps)
+    assert paused.value.node_id == "research"
+    assert paused.value.pending_input["toolCallId"] == "clarify-1"
+
+    result, _events = await _run(
+        graph,
+        {"topic": "新能源车"},
+        deps=deps,
+        resume_payload={
+            "nodeId": "research",
+            "values": {"answer": "中国市场"},
+            "message": "只分析中国市场",
+        },
+    )
+    assert result.output == {"text": "已按中国市场范围完成分析。"}
+    assert seen_resume_payloads == [None, {"nodeId": "research", "values": {"answer": "中国市场"}, "message": "只分析中国市场"}]
+
+
 @pytest.mark.asyncio
 async def test_agent_node_includes_rendered_workflow_input_bindings() -> None:
     seen: dict[str, Any] = {}