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/core.py

@@ -311,6 +311,25 @@ class AgentRuntime:
                 except (json.JSONDecodeError, TypeError):
                     targs = {}
 
+                # 工具执行前审批检查
+                if tname in self.config.tools.require_approval:
+                    from app.services.approval_manager import approval_manager as _am
+                    logger.info("Agent 工具需审批 [%s]: %s", tname, targs)
+                    approval_req = await _am.submit(
+                        tool_name=tname, args=targs,
+                        timeout_ms=self.config.tools.approval_timeout_ms,
+                    )
+                    decision = approval_req.decision
+                    if decision == "denied":
+                        result = f"[审批拒绝] 工具 {tname} 需要人工审批但被拒绝。"
+                        self.context.add_tool_result(tcid, tname, result)
+                        continue
+                    elif decision == "skip":
+                        result = f"[审批跳过] 工具 {tname} 被跳过。"
+                        self.context.add_tool_result(tcid, tname, result)
+                        continue
+                    # decision == "approved" → 继续执行
+
                 logger.info("Agent 执行工具 [%s]: %s", tname, targs)
                 result = await self.tool_manager.execute(tname, targs)
 
@@ -591,6 +610,34 @@ class AgentRuntime:
                     "iteration": self.context.iteration,
                 }
 
+                # 工具执行前审批检查（流式：先 create → yield 事件带 ID → 等待决定）
+                if tname in self.config.tools.require_approval:
+                    from app.services.approval_manager import approval_manager as _am
+                    logger.info("Agent 工具需审批 [%s]: %s", tname, targs)
+                    approval_req = _am.create(tool_name=tname, args=targs)
+                    yield {
+                        "type": "approval_required",
+                        "approval_id": approval_req.approval_id,
+                        "tool_name": tname,
+                        "args": targs,
+                        "iteration": self.context.iteration,
+                    }
+                    decision = await _am.wait_for_decision(
+                        approval_req.approval_id,
+                        timeout_ms=self.config.tools.approval_timeout_ms,
+                    )
+                    if decision == "denied":
+                        result = f"[审批拒绝] 工具 {tname} 需要人工审批但被拒绝。"
+                        yield {"type": "tool_result", "name": tname, "result": result, "iteration": self.context.iteration}
+                        self.context.add_tool_result(tcid, tname, result)
+                        continue
+                    elif decision == "skip":
+                        result = f"[审批跳过] 工具 {tname} 被跳过。"
+                        yield {"type": "tool_result", "name": tname, "result": result, "iteration": self.context.iteration}
+                        self.context.add_tool_result(tcid, tname, result)
+                        continue
+                    # decision == "approved" → 继续执行
+
                 logger.info("Agent 执行工具 [%s]: %s", tname, targs)
                 result = await self.tool_manager.execute(tname, targs)