Add validators and services for Product Galleries and Product Tags

- Implemented Create, Delete, Get, and Update validators for Product Galleries.
- Added Create, Delete, Get, and Update validators for Product Tags.
- Created service classes for handling Discount Categories, Discount Orders, Discount Products, Discount Shopping Cart, Product Categories, Product Galleries, and Product Tags.
- Each service class integrates with CQRS for command and query handling.
- Established mapping profiles for Product Galleries.

src/CMSMicroservice.Application/OrderVATCQ/Queries/GetOrderVAT/GetOrderVATQueryHandler.cs

@@ -0,0 +1,52 @@
+using CMSMicroservice.Application.Common.Interfaces;
+using MediatR;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+
+namespace CMSMicroservice.Application.OrderVATCQ.Queries.GetOrderVAT;
+
+public class GetOrderVATQueryHandler : IRequestHandler<GetOrderVATQuery, OrderVATDto?>
+{
+    private readonly IApplicationDbContext _context;
+    private readonly ILogger<GetOrderVATQueryHandler> _logger;
+
+    public GetOrderVATQueryHandler(
+        IApplicationDbContext context,
+        ILogger<GetOrderVATQueryHandler> logger)
+    {
+        _context = context;
+        _logger = logger;
+    }
+
+    public async Task<OrderVATDto?> Handle(GetOrderVATQuery request, CancellationToken cancellationToken)
+    {
+        var orderVAT = await _context.OrderVATs
+            .Where(x => x.OrderId == request.OrderId && !x.IsDeleted)
+            .Select(x => new OrderVATDto
+            {
+                Id = x.Id,
+                OrderId = x.OrderId,
+                VATRate = x.VATRate,
+                VATRatePercentage = $"{x.VATRate * 100:F1}%",
+                BaseAmount = x.BaseAmount,
+                VATAmount = x.VATAmount,
+                TotalAmount = x.TotalAmount,
+                IsPaid = x.IsPaid,
+                PaidAt = x.PaidAt,
+                Note = x.Note,
+                Created = x.Created
+            })
+            .FirstOrDefaultAsync(cancellationToken);
+
+        if (orderVAT != null)
+        {
+            _logger.LogInformation(
+                "Retrieved VAT for order {OrderId}. VAT Amount: {VATAmount}",
+                request.OrderId,
+                orderVAT.VATAmount
+            );
+        }
+
+        return orderVAT;
+    }
+}