feat(order): 添加重复购买检测功能

- 新增 DuplicatePurchaseException 类用于处理重复购买异常
- 在 OrderServiceImpl 中实现重复购买检查逻辑
- 更新 CustomExceptionHandle 以处理新的重复购买异常
-优化订单创建流程，在生成订单号前增加重复购买检查

src/main/java/com/ycwl/basic/order/exception/DuplicatePurchaseException.java

@@ -0,0 +1,58 @@
+package com.ycwl.basic.order.exception;
+
+import com.ycwl.basic.exception.BaseException;
+import com.ycwl.basic.pricing.enums.ProductType;
+
+/**
+ * 重复购买异常
+ * 当用户尝试购买已经购买过的内容时抛出此异常
+ */
+public class DuplicatePurchaseException extends BaseException {
+    
+    private final Long existingOrderId;
+    private final String existingOrderNo;
+    private final ProductType productType;
+    private final String productId;
+    
+    public DuplicatePurchaseException(String message, Long existingOrderId, String existingOrderNo, 
+                                     ProductType productType, String productId) {
+        super(message);
+        this.existingOrderId = existingOrderId;
+        this.existingOrderNo = existingOrderNo;
+        this.productType = productType;
+        this.productId = productId;
+    }
+    
+    public DuplicatePurchaseException(String message, Long existingOrderId, String existingOrderNo, 
+                                     ProductType productType) {
+        this(message, existingOrderId, existingOrderNo, productType, null);
+    }
+    
+    public Long getExistingOrderId() {
+        return existingOrderId;
+    }
+    
+    public String getExistingOrderNo() {
+        return existingOrderNo;
+    }
+    
+    public ProductType getProductType() {
+        return productType;
+    }
+    
+    public String getProductId() {
+        return productId;
+    }
+    
+    /**
+     * 获取友好的错误消息
+     */
+    public String getFriendlyMessage() {
+        String productDesc = productType != null ? productType.getDescription() : "商品";
+        if (productId != null) {
+            return String.format("您已购买过该%s（商品ID：%s），订单号：%s", productDesc, productId, existingOrderNo);
+        } else {
+            return String.format("您已购买过%s，订单号：%s", productDesc, existingOrderNo);
+        }
+    }
+}