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/ConfigurationCQ/Commands/SeedVATConfiguration/SeedVATConfigurationCommand.cs

@@ -0,0 +1,77 @@
+using CMSMicroservice.Application.Common.Interfaces;
+using CMSMicroservice.Domain.Enums;
+using MediatR;
+using Microsoft.Extensions.Logging;
+
+namespace CMSMicroservice.Application.ConfigurationCQ.Commands.SeedVATConfiguration;
+
+/// <summary>
+/// Seed initial VAT configuration
+/// نرخ مالیات پیش‌فرض ۹٪
+/// </summary>
+public class SeedVATConfigurationCommand : IRequest<Unit>
+{
+}
+
+public class SeedVATConfigurationCommandHandler : IRequestHandler<SeedVATConfigurationCommand, Unit>
+{
+    private readonly IApplicationDbContext _context;
+    private readonly ILogger<SeedVATConfigurationCommandHandler> _logger;
+
+    public SeedVATConfigurationCommandHandler(
+        IApplicationDbContext context,
+        ILogger<SeedVATConfigurationCommandHandler> logger)
+    {
+        _context = context;
+        _logger = logger;
+    }
+
+    public async Task<Unit> Handle(SeedVATConfigurationCommand request, CancellationToken cancellationToken)
+    {
+        var configs = new[]
+        {
+            new
+            {
+                Scope = ConfigurationScope.VAT,
+                Key = "Rate",
+                Value = "0.09",
+                Description = "نرخ مالیات بر ارزش افزوده (۹٪)"
+            },
+            new
+            {
+                Scope = ConfigurationScope.VAT,
+                Key = "IsEnabled",
+                Value = "true",
+                Description = "فعال/غیرفعال بودن محاسبه مالیات"
+            }
+        };
+
+        foreach (var config in configs)
+        {
+            var exists = _context.SystemConfigurations
+                .Any(x => x.Scope == config.Scope && x.Key == config.Key);
+
+            if (!exists)
+            {
+                _context.SystemConfigurations.Add(new Domain.Entities.Configuration.SystemConfiguration
+                {
+                    Scope = config.Scope,
+                    Key = config.Key,
+                    Value = config.Value,
+                    Description = config.Description
+                });
+
+                _logger.LogInformation(
+                    "VAT configuration seeded: {Scope}.{Key} = {Value}",
+                    config.Scope,
+                    config.Key,
+                    config.Value
+                );
+            }
+        }
+
+        await _context.SaveChangesAsync(cancellationToken);
+
+        return Unit.Value;
+    }
+}