修复: Wave5 审批子系统收尾（R7补 types.ts + R9⑪ failed_node + R8 Request 测试）

- R7补: types.ts event.type string→WorkflowEventType 字面量联合(11 变体 snake_case)，静态拦截写错 type
- R9⑪: workflow.rs WorkflowFailed failed_node String::new()→状态机取首个 Failed/Cancelled 节点
- R8: human_node 加 request_is_emitted_to_bus 测试，验证 R6(Request 真发到 EventBus)
cargo/vue-tsc 0 err / df-nodes 15 test pass

src-tauri/src/commands/workflow.rs

@@ -132,11 +132,20 @@ pub async fn run_workflow(
         state_registry.lock().await.remove(&exec_id);
 
         // 执行失败时补发 WorkflowFailed（执行器内部只发 NodeFailed）
+        // failed_node 从状态机取首个失败/取消节点(R9⑪: 原 String::new() 空值)
         if let Some(error) = error {
+            use df_core::types::NodeStatus;
+            let failed_node = executor
+                .state_machine()
+                .snapshot()
+                .into_iter()
+                .find(|(_, s)| matches!(s, NodeStatus::Failed | NodeStatus::Cancelled))
+                .map(|(id, _)| id)
+                .unwrap_or_default();
             event_bus
                 .send(WorkflowEvent::WorkflowFailed {
                     error,
-                    failed_node: String::new(),
+                    failed_node,
                 })
                 .await;
         }