修复: B-03b-R6 human_node send 缺 await + R7 前端契约失配（P0 审批链断裂）

R6: human_node.rs:41 发 HumanApprovalRequest 缺 .await（async fn send 的 Future 被 let _ = 丢弃未 poll，Request 从未进 channel，审批链最上游断裂，B-03a 重写引入，7 单测不覆盖 Request 发出故漏）
R7: project.ts:214 type 'HumanApprovalRequest'→'human_approval_request'(serde rename snake_case) + :215 payload.event.data→payload.event 扁平取字段(WorkflowEvent 无 data 包装)
来源: workflow-approval-review-2026-06-14.md §0/§1(31-agent 审查头号 P0)；cargo/vue-tsc 0 err / df-nodes 14 test pass

crates/df-nodes/src/human_node.rs

@@ -38,13 +38,16 @@ impl Node for HumanNode {
         let mut rx = ctx.event_bus.subscribe();
 
         // 2. 发送人工审批请求到事件总线
-        let _ = ctx.event_bus.send(WorkflowEvent::HumanApprovalRequest {
-            execution_id: ctx.execution_id.clone(),
-            node_id: ctx.node_id.clone(),
-            title: title.to_string(),
-            description: description.to_string(),
-            options: options.clone(),
-        });
+        // send 是 async fn(broadcast 同步发但 async 包装),必须 await 否则 Future 不 poll、Request 不进 channel(B-03b-R6)
+        let _ = ctx.event_bus
+            .send(WorkflowEvent::HumanApprovalRequest {
+                execution_id: ctx.execution_id.clone(),
+                node_id: ctx.node_id.clone(),
+                title: title.to_string(),
+                description: description.to_string(),
+                options: options.clone(),
+            })
+            .await;
 
         // 3. select! 循环：Response / 超时 / 取消
         let deadline = tokio::time::Instant::now() + Duration::from_secs(timeout_secs);