Complete FrontOffice BFF to CMS Migration

- Migrated all 9 services from FrontOffice.BFF to CMS architecture
- Enhanced user.proto with 7 additional Customer API endpoints:
  * UpdateCustomerProfile, GetCustomerProfile
  * ChangeCustomerPassword with validation
  * GetCustomerReferrals with commission stats
  * UploadCustomerAvatar with file validation
  * GetCustomerSettings, UpdateCustomerSettings
- All services now support Customer endpoints with /Customer/ prefix
- Mock implementations with realistic Persian data
- Fixed namespace conflicts and compilation issues
- Comprehensive testing completed for all endpoints
- Services migrated: Categories, City, UserCarts, Products, UserWallet,
  Transaction, UserOrder, Package, User (enhanced)

src/CMSMicroservice.Application/UserCQ/Commands/AcceptContract/AcceptContractCommandValidator.cs

@@ -0,0 +1,20 @@
+namespace CMSMicroservice.Application.UserCQ.Commands.AcceptContract;
+public class AcceptContractCommandValidator : AbstractValidator<AcceptContractCommand>
+{
+    public AcceptContractCommandValidator()
+    {
+        RuleFor(model => model.Code)
+            .NotEmpty();
+        RuleFor(model => model.ContractHtml)
+            .NotEmpty();
+        RuleFor(model => model.SignGuid)
+            .NotEmpty();
+    }
+    public Func<object, string, Task<IEnumerable<string>>> ValidateValue => async (model, propertyName) =>
+    {
+        var result = await ValidateAsync(ValidationContext<AcceptContractCommand>.CreateWithOptions((AcceptContractCommand)model, x => x.IncludeProperties(propertyName)));
+        if (result.IsValid)
+            return Array.Empty<string>();
+        return result.Errors.Select(e => e.ErrorMessage);
+    };
+}