feat: Implement Discount Product and Shopping Cart functionalities

- Added UpdateDiscountProductCommandValidator for validating discount product updates.
- Created GetDiscountProductByIdQuery and its handler for retrieving discount product details by ID.
- Implemented GetDiscountProductsQuery and handler for fetching a list of discount products with filtering options.
- Developed AddToCartCommand and handler for adding products to the shopping cart.
- Implemented ClearCartCommand and handler for clearing the shopping cart.
- Created RemoveFromCartCommand and handler for removing items from the cart.
- Added UpdateCartItemCountCommand and handler for updating the quantity of items in the cart.
- Developed GetUserCartQuery and handler for retrieving the user's shopping cart details.
- Implemented Product Tag functionalities including assigning tags to products, creating, updating, and deleting tags.
- Added queries for fetching all tags and products by tag.

src/BackOffice.BFF.Application/DiscountOrderCQ/Queries/GetOrderById/GetOrderByIdQueryHandler.cs

@@ -0,0 +1,58 @@
+using CMSMicroservice.Protobuf.Protos.DiscountOrder;
+
+namespace BackOffice.BFF.Application.DiscountOrderCQ.Queries.GetOrderById;
+
+public class GetOrderByIdQueryHandler : IRequestHandler<GetOrderByIdQuery, GetOrderByIdResponseDto>
+{
+    private readonly IApplicationContractContext _context;
+
+    public GetOrderByIdQueryHandler(IApplicationContractContext context)
+    {
+        _context = context;
+    }
+
+    public async Task<GetOrderByIdResponseDto> Handle(GetOrderByIdQuery request, CancellationToken cancellationToken)
+    {
+        var response = await _context.DiscountOrders.GetOrderByIdAsync(
+            new GetOrderByIdRequest { OrderId = request.OrderId },
+            cancellationToken: cancellationToken);
+
+        return new GetOrderByIdResponseDto
+        {
+            Id = response.Id,
+            UserId = response.UserId,
+            TrackingCode = response.TrackingCode,
+            Status = response.Status,
+            StatusTitle = response.StatusTitle,
+            TotalPrice = response.TotalPrice,
+            DiscountBalanceUsed = response.DiscountBalanceUsed,
+            GatewayPayment = response.GatewayPayment,
+            FinalPrice = response.FinalPrice,
+            PaymentTransactionCode = response.PaymentTransactionCode,
+            AdminNote = response.AdminNote,
+            CreatedAt = response.CreatedAt.ToDateTime(),
+            PaidAt = response.HasPaidAt ? response.PaidAt.ToDateTime() : null,
+            ShippingAddress = new AddressInfoDto
+            {
+                Id = response.ShippingAddress.Id,
+                RecipientName = response.ShippingAddress.RecipientName,
+                RecipientPhone = response.ShippingAddress.RecipientPhone,
+                Province = response.ShippingAddress.Province,
+                City = response.ShippingAddress.City,
+                PostalCode = response.ShippingAddress.PostalCode,
+                FullAddress = response.ShippingAddress.FullAddress
+            },
+            Items = response.Items.Select(item => new OrderItemDto
+            {
+                Id = item.Id,
+                ProductId = item.ProductId,
+                ProductTitle = item.ProductTitle,
+                UnitPrice = item.UnitPrice,
+                DiscountPercent = item.DiscountPercent,
+                Quantity = item.Quantity,
+                TotalPrice = item.TotalPrice,
+                DiscountedPrice = item.DiscountedPrice
+            }).ToList()
+        };
+    }
+}