feat: Phase 2 - Orchestrator workflow node + tool-level human approval

2.1 Orchestrator in workflow:
- New run_orchestrator_node() in workflow_integration.py loads agents from DB,
  supports route/sequential/debate/pipeline modes
- New 'orchestrator' node type in workflow_engine.py execute_node dispatch

2.2 Tool-level human approval:
- AgentToolConfig extended with require_approval, approval_timeout_ms,
  approval_default fields
- New ApprovalManager (approval_manager.py) with asyncio.Event-based
  create/wait_for_decision/resolve pattern
- AgentRuntime run() and run_stream() intercept tool execution,
  wait for approval decision before executing
- New POST /api/v1/approval/{id}/resolve REST endpoint
- Frontend: approval_required SSE event handling, approval dialog UI
  with approve/deny/skip buttons

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/views/AgentChat.vue

@@ -204,6 +204,22 @@
         <el-button @click="showOrchestrateEditor = false">关闭</el-button>
       </template>
     </el-dialog>
+
+    <!-- 工具审批对话框 -->
+    <el-dialog v-model="showApprovalDialog" title="工具执行审批" width="480px" :close-on-click-modal="false">
+      <div style="margin-bottom: 12px">
+        <el-tag type="warning" size="large">{{ approvalToolName }}</el-tag>
+        <span style="margin-left: 8px; color: #666">需要人工审批才能执行</span>
+      </div>
+      <div v-if="Object.keys(approvalArgs).length > 0" style="background: #f5f7fa; padding: 12px; border-radius: 6px; max-height: 200px; overflow-y: auto">
+        <pre style="margin: 0; font-size: 13px; white-space: pre-wrap; word-break: break-all">{{ JSON.stringify(approvalArgs, null, 2) }}</pre>
+      </div>
+      <template #footer>
+        <el-button @click="resolveApproval('denied')">拒绝</el-button>
+        <el-button @click="resolveApproval('skip')">跳过</el-button>
+        <el-button type="primary" @click="resolveApproval('approved')">批准执行</el-button>
+      </template>
+    </el-dialog>
   </MainLayout>
 </template>
 
@@ -249,6 +265,18 @@ interface ChatState {
   orchestrateAgents: OrchestrateAgentForm[]
 }
 
+async function resolveApproval(decision: string) {
+  try {
+    await api.post(`/api/v1/approval/${approvalId.value}/resolve`, { decision })
+  } catch {
+    // 审批已超时或已处理，忽略
+  }
+  showApprovalDialog.value = false
+  approvalId.value = ''
+  approvalToolName.value = ''
+  approvalArgs.value = {}
+}
+
 function saveState() {
   try {
     const state: ChatState = {
@@ -285,6 +313,11 @@ const messages = ref<Record<string, ChatMessage[]>>({})
 const inputMessage = ref('')
 const loading = ref(false)
 const streamingActive = ref(false)
+// 工具审批状态
+const showApprovalDialog = ref(false)
+const approvalId = ref('')
+const approvalToolName = ref('')
+const approvalArgs = ref<Record<string, any>>({})
 const messagesRef = ref<HTMLElement | null>(null)
 const sessionId = ref<Record<string, string>>({})
 const agent = ref<Agent | null>(null)
@@ -486,6 +519,11 @@ async function sendMessage() {
                     tool_name: data.name,
                     tool_result: data.result,
                   })
+                } else if (eventType === 'approval_required') {
+                  approvalId.value = data.approval_id || ''
+                  approvalToolName.value = data.tool_name || ''
+                  approvalArgs.value = data.args || {}
+                  showApprovalDialog.value = true
                 } else if (eventType === 'final') {
                   currentMsg.content = data.content || ''
                   currentMsg.iterations = data.iterations_used || 0