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/Commands/PlaceOrder/PlaceOrderCommand.cs

@@ -0,0 +1,16 @@
+namespace BackOffice.BFF.Application.DiscountOrderCQ.Commands.PlaceOrder;
+
+public record PlaceOrderCommand : IRequest<PlaceOrderResponseDto>
+{
+    /// <summary>شناسه کاربر</summary>
+    public long UserId { get; init; }
+    
+    /// <summary>شناسه آدرس ارسال</summary>
+    public long AddressId { get; init; }
+    
+    /// <summary>مبلغ پرداخت از موجودی تخفیف</summary>
+    public long DiscountBalanceAmount { get; init; }
+    
+    /// <summary>مبلغ پرداخت از درگاه</summary>
+    public long GatewayAmount { get; init; }
+}

src/BackOffice.BFF.Application/DiscountOrderCQ/Commands/PlaceOrder/PlaceOrderCommandHandler.cs

@@ -0,0 +1,34 @@
+using CMSMicroservice.Protobuf.Protos.DiscountOrder;
+
+namespace BackOffice.BFF.Application.DiscountOrderCQ.Commands.PlaceOrder;
+
+public class PlaceOrderCommandHandler : IRequestHandler<PlaceOrderCommand, PlaceOrderResponseDto>
+{
+    private readonly IApplicationContractContext _context;
+
+    public PlaceOrderCommandHandler(IApplicationContractContext context)
+    {
+        _context = context;
+    }
+
+    public async Task<PlaceOrderResponseDto> Handle(PlaceOrderCommand request, CancellationToken cancellationToken)
+    {
+        var response = await _context.DiscountOrders.PlaceOrderAsync(
+            new PlaceOrderRequest
+            {
+                UserId = request.UserId,
+                AddressId = request.AddressId,
+                DiscountBalanceAmount = request.DiscountBalanceAmount,
+                GatewayAmount = request.GatewayAmount
+            },
+            cancellationToken: cancellationToken);
+
+        return new PlaceOrderResponseDto
+        {
+            OrderId = response.OrderId,
+            TrackingCode = response.TrackingCode,
+            RequiresGatewayPayment = response.RequiresGatewayPayment,
+            GatewayPayableAmount = response.GatewayPayableAmount
+        };
+    }
+}

src/BackOffice.BFF.Application/DiscountOrderCQ/Commands/PlaceOrder/PlaceOrderCommandValidator.cs

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+namespace BackOffice.BFF.Application.DiscountOrderCQ.Commands.PlaceOrder;
+
+public class PlaceOrderCommandValidator : AbstractValidator<PlaceOrderCommand>
+{
+    public PlaceOrderCommandValidator()
+    {
+        RuleFor(x => x.UserId)
+            .GreaterThan(0).WithMessage("شناسه کاربر نامعتبر است");
+
+        RuleFor(x => x.AddressId)
+            .GreaterThan(0).WithMessage("شناسه آدرس نامعتبر است");
+
+        RuleFor(x => x.DiscountBalanceAmount)
+            .GreaterThanOrEqualTo(0).WithMessage("مبلغ موجودی تخفیف نمی‌تواند منفی باشد");
+
+        RuleFor(x => x.GatewayAmount)
+            .GreaterThanOrEqualTo(0).WithMessage("مبلغ درگاه نمی‌تواند منفی باشد");
+
+        RuleFor(x => x)
+            .Must(x => x.DiscountBalanceAmount + x.GatewayAmount > 0)
+            .WithMessage("مجموع مبالغ پرداخت باید بیشتر از صفر باشد");
+    }
+}

src/BackOffice.BFF.Application/DiscountOrderCQ/Commands/PlaceOrder/PlaceOrderResponseDto.cs

@@ -0,0 +1,16 @@
+namespace BackOffice.BFF.Application.DiscountOrderCQ.Commands.PlaceOrder;
+
+public class PlaceOrderResponseDto
+{
+    /// <summary>شناسه سفارش</summary>
+    public long OrderId { get; set; }
+    
+    /// <summary>کد پیگیری سفارش</summary>
+    public string TrackingCode { get; set; }
+    
+    /// <summary>آیا نیاز به پرداخت از درگاه دارد</summary>
+    public bool RequiresGatewayPayment { get; set; }
+    
+    /// <summary>مبلغ قابل پرداخت از درگاه</summary>
+    public long GatewayPayableAmount { get; set; }
+}