fix(trader): cancel_order 补 symbol/exchange

vnpy 4.4.0 的 CancelRequest 必填 (orderid,symbol,exchange)，原代码只传
orderid → TypeError → 撤单从不工作。改为从 _exec.orders 缓存查 OrderData
拿 symbol/exchange 一起传。E2E 实证 {ok:True} 无 TypeError（盘后 miniQMT
非交易时段不实际撤单，是另一回事）。

sanguo_trader/qmt_gateway_client.py

@@ -164,9 +164,14 @@ class QmtGatewayClient:
         try:
             from vnpy.trader.object import CancelRequest
             oid = str(order_id)
-            if oid.startswith("QMT."):      # vt_orderid(QMT.184246#1)→ remark(184246#1)
-                oid = oid[4:]                # vnpy_qmt td.orders 按 remark 建 key
-            self._exec.gateway.cancel_order(CancelRequest(orderid=oid))
+            vt = oid if oid.startswith("QMT.") else f"QMT.{oid}"
+            o = self._exec.orders.get(vt)
+            if o is None:
+                return {"ok": False, "error": f"order {oid} 不在缓存（gateway 未收到该单事件）"}
+            remark = vt[4:]   # vt_orderid(QMT.184246#1)→ remark(184246#1)，vnpy_qmt 按 remark 建 key
+            # vnpy 4.4.0 的 CancelRequest 必填 (orderid, symbol, exchange)，缺 symbol/exchange 会 TypeError
+            self._exec.gateway.cancel_order(
+                CancelRequest(orderid=remark, symbol=o.symbol, exchange=o.exchange))
             return {"ok": True, "order_id": order_id}
         except Exception as e:  # noqa: BLE001
             logger.warning("QmtGatewayClient.cancel_order 失败 %s: %s", order_id, e)