Refactor activation handling and introduce entity system

Added new `ActivationHandler` class for folder initialization.
Added `ProjectService` class for project-related operations.
Added `Ghost.Entities` project with entity management classes.
Added `EngineEditorWindow` for enhanced user interface.

Changed project files to restructure dependencies and remove unused references.
Changed `ProjectRepository` to use asynchronous methods for improved performance.
Changed data binding in `CreateProjectPage.xaml` and `OpenProjectPage.xaml` to use new data models.
Changed `App.xaml.cs` to utilize the new `ActivationHandler` and include additional services.

Removed `IActivationHandler` interface and integrated its functionality into `ActivationHandler`.
Removed `EditorActivationHandler` as its functionality was merged into `ActivationHandler`.

Updated `AssemblyInfo.cs` to include global using directives for entity types.
Updated image assets to reflect visual resource changes.

Ghost.Core/Activation/ActivationHandler.cs

@@ -1,13 +0,0 @@
-namespace Ghost.Core.Activation;
-
-public abstract class ActivationHandler<T> : IActivationHandler
-    where T : class
-{
-    protected virtual bool CanHandleInternal(T args) => true;
-
-    protected abstract Task HandleInternalAsync(T args);
-
-    public bool CanHandle(object args) => args is T && CanHandleInternal((args as T)!);
-
-    public async Task HandleAsync(object args) => await HandleInternalAsync((args as T)!);
-}

Ghost.Core/Activation/IActivationHandler.cs

@@ -1,8 +0,0 @@
-namespace Ghost.Core.Activation;
-
-public interface IActivationHandler
-{
-    bool CanHandle(object args);
-
-    Task HandleAsync(object args);
-}

Ghost.Core/Ghost.Core.csproj

@@ -1,9 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <TargetFramework>net9.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-  </PropertyGroup>
-
-</Project>