Refactor

[celeron533]

This pull request modernizes the window management and interop layers of the application by migrating from the deprecated PInvoke and custom NativeMethods to the official Windows.Win32 (CsWin32) interop library. It also improves resource management, updates the build pipeline to use the .NET SDK with dotnet CLI, and removes legacy dependencies. The most important changes are grouped below:

Migration to Windows.Win32 (CsWin32) Interop

• Replaced all usages of PInvoke and custom NativeMethods with the official Windows.Win32 interop APIs in WindowInstanceInfo, WindowInstanceUtil, and related files, updating types (e.g., IntPtr to HWND) and method calls accordingly. (Stealth/Core/WindowInstanceInfo.cs, Stealth/Core/WindowInstanceUtil.cs, [1] [2] [3] [4] [5] [6] [7] [8]
• Removed the now-unnecessary Stealth/Core/NativeMethods.cs file.

Resource Management Improvements

• Added proper disposal of window icon bitmaps and implemented IDisposable in WindowInstanceInfo to prevent resource leaks. (Stealth/Core/WindowInstanceInfo.cs, [1] [2]

Build Pipeline Modernization

• Updated the GitHub Actions workflow to use the .NET SDK (dotnet restore, dotnet build, dotnet test) instead of MSBuild/NuGet, set the solution file path, and replaced deprecated actions with their latest versions. (.github/workflows/msbuild.yml, [1] [2]

Dependency and Code Cleanup

• Removed the unused GalaSoft.MvvmLight and related dispatcher initialization code from App.xaml.cs and MainService.cs. (Stealth/App.xaml.cs, [1] [2]; Stealth/Model/MainService.cs, [3]
• Removed the System.Runtime.CompilerServices.Unsafe binding redirect from App.config as it is no longer needed. (Stealth/App.config, Stealth/App.configL16-L19)

Data Model and Event Handling Improvements

• Ensured that the returned window info collection is a new instance and attached property change handlers to new items for proper MVVM updates. (Stealth/Model/MainService.cs, [1] [2]