feat: 重构订单路由逻辑，添加订单意图类型以支持多交易所订单处理

src/exchanges/paradex/gateway.ts

@@ -602,6 +602,9 @@ export class ParadexGateway {
       // Only omit amount for MARKET close-position orders; STOP requires explicit size
       const shouldOmitAmount = isClosePosition && type === "market";
       const amountArg: any = shouldOmitAmount ? undefined : amount;
+      if (!shouldOmitAmount && amountArg != null && extraParams.size === undefined) {
+        extraParams.size = amountArg.toString();
+      }
       const order = (await this.exchange.createOrder(
         symbol,
         type,