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/MainWindow.xaml

@@ -0,0 +1,12 @@
+<Window x:Class="SharepointToolbox.MainWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:local="clr-namespace:SharepointToolbox"
+        mc:Ignorable="d"
+        Title="MainWindow" Height="450" Width="800">
+    <Grid>
+
+    </Grid>
+</Window>