Enhance framework compatibility and code readability

Added preprocessor directives for .NET framework compatibility.
Modified `using` directives to be framework-specific.
Improved code formatting for better readability.
Introduced obsolete attributes for deprecated methods,
recommending `MediatR` as an alternative.
Added XML documentation for clarity and maintainability.

DigitalData.Core.Abstraction.Application/Repository/ICRUDRepository.cs

@@ -1,4 +1,5 @@
-namespace DigitalData.Core.Abstraction.Application.Repository
+#if NET
+namespace DigitalData.Core.Abstraction.Application.Repository
 {
     /// <summary>
     /// Defines the contract for CRUD operations on a repository for entities of type TEntity.
@@ -60,4 +61,5 @@
         /// </remarks>
         Task<int> CountAsync(TId id);
     }
-}
+}
+#endif