feat: ReadService hinzugefügt und in ReadController integriert

- Generischen ReadService erstellt, um Lese- (ReadById, ReadAll) und Löschoperationen zu verwalten.
- ReadService in den ReadController integriert.

DigitalData.Core.DTO/AutoMapperExtension.cs

@@ -1,23 +0,0 @@
-using AutoMapper;
-
-namespace DigitalData.Core.DTO
-{
-    public static class AutoMapperExtension
-    {
-        [Obsolete("use mapper.Map<T>")]
-        /// <summary>
-        /// Maps a source object to a destination object, or throws an exception if the mapping result is null.
-        /// </summary>
-        /// <typeparam name="TSource">The source object type.</typeparam>
-        /// <typeparam name="TDestination">The destination object type.</typeparam>
-        /// <param name="source">The source object to map from.</param>
-        /// <returns>The mapped destination object.</returns>
-        /// <exception cref="MappingResultNullException">Thrown when the mapping result is null.</exception>
-        public static TDestination MapOrThrow<TDestination>(this IMapper mapper, object source)
-        {
-            return mapper.Map<TDestination>(source) ?? throw new AutoMapperMappingException(
-                $"Mapping to {typeof(TDestination).FullName} resulted in a null object. " +
-                   "Hint: Ensure that the AutoMapper profile configuration for this mapping is correct.");
-        }
-    }
-}