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

crates/df-nodes/src/human_node.rs

@@ -195,6 +195,40 @@ mod tests {
         assert_eq!(out.data["comment"], json!("好的"));
     }
 
+    #[tokio::test]
+    async fn request_is_emitted_to_bus() {
+        // B-03b-R8: 验证 HumanNode 真发出 HumanApprovalRequest 到事件总线
+        // (R6 修复前 :41 send 缺 await → Request 未进 channel，此测会超时失败)
+        let bus = EventBus::new();
+        let mut rx = bus.subscribe(); // subscribe 先于 execute send(broadcast 不回放)
+        let ctx = make_ctx(&bus, "exec-1", "node-h", json!({ "timeout_secs": 1 }));
+        let bus_clone = bus.clone();
+        let handle = tokio::spawn(async move { HumanNode.execute(ctx).await });
+
+        // execute send Request 后 rx 应收到
+        let received = tokio::time::timeout(Duration::from_millis(500), rx.recv()).await;
+        assert!(
+            received.is_ok(),
+            "应收到 HumanApprovalRequest(R6 Request 真发出)，实际超时"
+        );
+        match received.unwrap().unwrap() {
+            WorkflowEvent::HumanApprovalRequest {
+                execution_id,
+                node_id,
+                title,
+                ..
+            } => {
+                assert_eq!(execution_id, "exec-1");
+                assert_eq!(node_id, "node-h");
+                assert_eq!(title, "请确认");
+            }
+            other => panic!("期望 HumanApprovalRequest，收到 {:?}", other),
+        }
+        // 发 Response 让 execute 正常返回(防 task 泄漏)
+        send_response(&bus_clone, "exec-1", "node-h", "同意", None).await;
+        let _ = handle.await;
+    }
+
     #[tokio::test]
     async fn mismatched_execution_id_filtered_then_timeout() {
         // execution_id 不匹配：Response 被过滤，短超时验证 → Err 超时