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>

backend/app/agent_runtime/workflow_integration.py

@@ -129,3 +129,163 @@ async def run_agent_node(
             "status": "error",
             "error": result.error,
         }
+
+
+async def run_orchestrator_node(
+    node_data: Dict[str, Any],
+    input_data: Dict[str, Any],
+    execution_logger: Optional[Any] = None,
+    user_id: Optional[str] = None,
+    on_tool_executed: Optional[Any] = None,
+    on_llm_invocation: Optional[Any] = None,
+) -> Dict[str, Any]:
+    """
+    在工作流中执行多 Agent 编排节点。
+
+    node_data 支持的字段：
+        mode              — "route" | "sequential" | "debate" | "pipeline"
+        agents            — Agent ID 列表（必填，至少 2 个）
+        routing_prompt    — route 模式的路由指令（可选）
+        aggregation_prompt— debate 模式的汇总指令（可选）
+        model             — 覆盖各 Agent 的模型（可选）
+        provider          — 覆盖各 Agent 的提供商（可选）
+        temperature       — 覆盖各 Agent 的温度（可选）
+        max_iterations    — 覆盖各 Agent 的最大步数（可选）
+
+    input_data 中的 "query" 或 "input" 字段作为用户输入。
+    """
+    from sqlalchemy.orm import Session
+    from app.core.database import SessionLocal
+    from app.models.agent import Agent
+    from app.agent_runtime.orchestrator import (
+        AgentOrchestrator,
+        OrchestratorAgentConfig,
+    )
+
+    # 1. 解析输入
+    query = (
+        input_data.get("query")
+        or input_data.get("input")
+        or input_data.get("text", "")
+    )
+    if not isinstance(query, str):
+        query = str(query) if query else ""
+
+    if not query:
+        return {"output": "错误：Orchestrator 节点未收到用户输入", "status": "error"}
+
+    # 2. 解析编排模式
+    mode = node_data.get("mode", "debate").lower()
+    if mode not in ("route", "sequential", "debate", "pipeline"):
+        return {"output": f"错误：不支持的编排模式 '{mode}'，可选: route, sequential, debate, pipeline", "status": "error"}
+
+    # 3. 解析 Agent 列表
+    agent_ids = node_data.get("agents", [])
+    if not agent_ids or not isinstance(agent_ids, list) or len(agent_ids) < 1:
+        return {"output": "错误：Orchestrator 节点需要至少 1 个 Agent", "status": "error"}
+
+    # 4. 从 DB 加载 Agent 配置
+    db: Optional[Session] = None
+    try:
+        db = SessionLocal()
+
+        # 覆盖配置（可选）
+        override_model = node_data.get("model")
+        override_provider = node_data.get("provider")
+        override_temperature = node_data.get("temperature")
+        override_max_iterations = node_data.get("max_iterations")
+
+        agent_configs: list = []
+        for agent_id in agent_ids:
+            agent = db.query(Agent).filter(Agent.id == agent_id).first()
+            if not agent:
+                logger.warning("Orchestrator: Agent %s 不存在，跳过", agent_id)
+                continue
+
+            # 从 workflow_config 提取 Agent 的 LLM 配置
+            wc = agent.workflow_config or {}
+            nodes = wc.get("nodes", [])
+            system_prompt = agent.description or ""
+            model = override_model or "deepseek-v4-flash"
+            provider = override_provider or "deepseek"
+            temperature = float(override_temperature) if override_temperature else 0.7
+            max_iterations = int(override_max_iterations) if override_max_iterations else 10
+            tools_whitelist: list = []
+
+            for n in nodes:
+                if n.get("type") not in ("agent", "llm", "template"):
+                    continue
+                cfg = n.get("data", {}) if isinstance(n, dict) else getattr(n, "data", {})
+                system_prompt = cfg.get("system_prompt", "") or system_prompt
+                if not override_model:
+                    model = cfg.get("model", model)
+                if not override_provider:
+                    provider = cfg.get("provider", provider)
+                if not override_temperature:
+                    temperature = float(cfg.get("temperature", temperature))
+                if not override_max_iterations:
+                    max_iterations = int(cfg.get("max_iterations", max_iterations))
+                tools_whitelist = cfg.get("tools", tools_whitelist)
+                break
+
+            agent_configs.append(OrchestratorAgentConfig(
+                id=agent.id,
+                name=agent.name or "Agent",
+                system_prompt=system_prompt,
+                model=model,
+                provider=provider,
+                temperature=temperature,
+                max_iterations=max_iterations,
+                tools=tools_whitelist,
+                description=agent.description or "",
+            ))
+
+        if not agent_configs:
+            return {"output": "错误：没有找到可用的 Agent", "status": "error"}
+
+        # 5. 创建 Orchestrator 并执行
+        orchestrator = AgentOrchestrator(
+            default_llm_config=AgentLLMConfig(
+                model=override_model or "deepseek-v4-flash",
+                temperature=0.3,
+            ),
+        )
+        result = await orchestrator.run(
+            mode=mode,
+            question=query,
+            agents=agent_configs,
+            on_llm_call=on_llm_invocation,
+        )
+
+        # 6. 返回结构化结果
+        return {
+            "output": result.final_answer,
+            "status": "success",
+            "orchestrator_meta": {
+                "mode": result.mode,
+                "agent_count": len(agent_configs),
+                "steps": [
+                    {
+                        "agent_id": s.agent_id,
+                        "agent_name": s.agent_name,
+                        "input": s.input[:200] if s.input else "",
+                        "output": s.output[:500] if s.output else "",
+                        "iterations_used": s.iterations_used,
+                        "tool_calls_made": s.tool_calls_made,
+                        "error": s.error,
+                    }
+                    for s in result.steps
+                ],
+            },
+        }
+
+    except Exception as e:
+        logger.error("Orchestrator 节点执行失败: %s", e, exc_info=True)
+        return {
+            "output": None,
+            "status": "failed",
+            "error": f"Orchestrator 执行失败: {e}",
+        }
+    finally:
+        if db:
+            db.close()