feat(Factory): add Factory class implementing IServiceProvider and IServiceCollection

- Introduced Factory class in DigitalData.Core.Abstractions namespace
- Implements both IServiceProvider and IServiceCollection interfaces
- Provides singleton instance via static readonly Instance property
- Supports lazy initialization of IServiceProvider using Lazy<T>
- Includes full collection management (Add, Remove, Clear, etc.)
- Ensures compatibility with both .NET and .NET Framework via conditional directives

DigitalData.Core.Abstractions/Factory.cs

@@ -0,0 +1,97 @@
+using Microsoft.Extensions.DependencyInjection;
+using System.Collections;
+#if NETFRAMEWORK
+using System;
+using System.Collections.Generic;
+#endif
+
+namespace DigitalData.Core.Abstractions
+{
+    public class Factory : IServiceProvider, IServiceCollection
+    {
+        public static readonly Factory Instance = new Factory();
+
+        private readonly IServiceCollection _serviceCollection = new ServiceCollection();
+
+        private readonly Lazy<IServiceProvider> _lazyServiceProvider;
+
+        public Factory()
+        {
+            _serviceCollection = new ServiceCollection();
+            _lazyServiceProvider = new Lazy<IServiceProvider>(() => _serviceCollection.BuildServiceProvider());
+        }
+
+        #region Service Provider
+        public object
+#if NET
+            ?
+#endif
+            GetService(Type serviceType)
+        {
+            return _lazyServiceProvider.Value;
+        }
+        #endregion
+
+        #region Service Collection
+        public int Count => _serviceCollection.Count;
+
+        public bool IsReadOnly => _serviceCollection.IsReadOnly;
+
+        public ServiceDescriptor this[int index]
+        {
+            get => _serviceCollection[index];
+            set => _serviceCollection[index] = value;
+        }
+
+        public int IndexOf(ServiceDescriptor item)
+        {
+            return _serviceCollection.IndexOf(item);
+        }
+
+        public void Insert(int index, ServiceDescriptor item)
+        {
+            _serviceCollection.Insert(index, item);
+        }
+
+        public void RemoveAt(int index)
+        {
+            _serviceCollection.RemoveAt(index);
+        }
+
+        public void Add(ServiceDescriptor item)
+        {
+            _serviceCollection.Add(item);
+        }
+
+        public void Clear()
+        {
+            _serviceCollection.Clear();
+        }
+
+        public bool Contains(ServiceDescriptor item)
+        {
+            return _serviceCollection.Contains(item);
+        }
+
+        public void CopyTo(ServiceDescriptor[] array, int arrayIndex)
+        {
+            _serviceCollection.CopyTo(array, arrayIndex);
+        }
+
+        public bool Remove(ServiceDescriptor item)
+        {
+            return _serviceCollection.Remove(item);
+        }
+
+        public IEnumerator<ServiceDescriptor> GetEnumerator()
+        {
+            return _serviceCollection.GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return (_serviceCollection as IEnumerable).GetEnumerator();
+        }
+        #endregion
+    }
+}