feat: update GetOrderByIdQuery to allow nullable UserId and adjust query handling in GetOrderByIdQueryHandler

src/CMSMicroservice.Application/DiscountShopCQ/Queries/GetOrderById/GetOrderByIdQueryHandler.cs

@@ -15,8 +15,15 @@ public class GetOrderByIdQueryHandler : IRequestHandler<GetOrderByIdQuery, Order
 
     public async Task<OrderDetailDto?> Handle(GetOrderByIdQuery request, CancellationToken cancellationToken)
     {
-        var order = await _context.DiscountOrders
-            .Where(o => o.Id == request.OrderId && o.UserId == request.UserId)
+        var query = _context.DiscountOrders
+            .Where(o => o.Id == request.OrderId);
+
+        if (request.UserId.HasValue && request.UserId.Value > 0)
+        {
+            query = query.Where(o => o.UserId == request.UserId.Value);
+        }
+
+        var order = await query
             .Include(o => o.UserAddress)
             .Include(o => o.OrderDetails)
                 .ThenInclude(od => od.Product)