feat(01-01): create WPF solution with Generic Host entry point and NuGet packages

- SharepointToolbox.slnx solution with WPF project
- net10.0-windows target, PublishTrimmed=false, StartupObject set
- App.xaml StartupUri removed, App demoted from ApplicationDefinition to Page
- App.xaml.cs: [STAThread] Main with Host.CreateDefaultBuilder + Serilog rolling file
- All NuGet packages: CommunityToolkit.Mvvm 8.4.2, MSAL 4.83.3, PnP.Framework 1.18.0, Serilog 4.3.1
- Build: 0 errors, 0 warnings

SharepointToolbox/App.xaml

@@ -0,0 +1,8 @@
+<Application x:Class="SharepointToolbox.App"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:local="clr-namespace:SharepointToolbox">
+    <Application.Resources>
+
+    </Application.Resources>
+</Application>