refactor: Entfernte nicht benötigte _keyPropertyInfo und aktualisierte CreateAsync Methode

- Entfernte `_keyPropertyInfo` und die zugehörige Methode `KeyValueOf`, da sie nicht mehr benötigt wird.
- Aktualisierte `CreateAsync` Methode, um direkt `createdEntity.Id` zurückzugeben.

DigitalData.Core.Application/CRUDService.cs

@@ -1,8 +1,6 @@
 using DigitalData.Core.Abstractions.Application;
 using DigitalData.Core.Abstractions.Infrastructure;
 using AutoMapper;
-using System.Reflection;
-using System.ComponentModel.DataAnnotations;
 using DigitalData.Core.DTO;
 using DigitalData.Core.Abstractions;
 using Microsoft.Extensions.Logging;
@@ -22,7 +20,6 @@ namespace DigitalData.Core.Application
     {
         protected readonly TCRUDRepository _repository;
         protected readonly IMapper _mapper;
-        protected readonly PropertyInfo? _keyPropertyInfo;
 
         /// <summary>
         /// Initializes a new instance of the CRUDService class with the specified repository, translation service, and mapper.
@@ -33,9 +30,6 @@ namespace DigitalData.Core.Application
         {
             _repository = repository;
             _mapper = mapper;
-
-            _keyPropertyInfo = typeof(TEntity).GetProperties()
-                .FirstOrDefault(prop => Attribute.IsDefined(prop, typeof(KeyAttribute)));
         }
 
         /// <summary>
@@ -47,7 +41,7 @@ namespace DigitalData.Core.Application
         {
             var entity = _mapper.Map<TEntity>(createDto);
             var createdEntity = await _repository.CreateAsync(entity);
-            return createdEntity is null ? Result.Fail<TId>() : Result.Success(KeyValueOf(createdEntity));
+            return createdEntity is null ? Result.Fail<TId>() : Result.Success(createdEntity.Id);
         }
 
         /// <summary>
@@ -120,24 +114,6 @@ namespace DigitalData.Core.Application
             return entity is not null;
         }
 
-        /// <summary>
-        /// Retrieves the ID value of an entity based on the defined [Key] attribute.
-        /// </summary>
-        /// <param name="entity">The entity from which to extract the ID.</param>
-        /// <returns>The ID of the entity.</returns>
-        protected virtual TId KeyValueOf(TEntity entity)
-        {
-            if (_keyPropertyInfo is null)
-                throw new InvalidOperationException($"No property with [Key] attribute found on {typeof(TEntity).Name} entity.");
-
-            object idObj = _keyPropertyInfo?.GetValue(entity) ?? throw new InvalidOperationException($"The ID property of {typeof(TEntity).Name} entity cannot be null.");
-
-            if (idObj is TId id)
-                return id;
-            else
-                throw new InvalidCastException($"The ID of {typeof(TEntity).Name} entity must be type of {typeof(TId).Name}, but it is type of {idObj.GetType().Name}.");
-        }
-
         /// <summary>
         /// Handles exceptions that occur during CRUD operations, providing a structured string.
         /// </summary>