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.slnx

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+<Solution>
+  <Project Path="SharepointToolbox/SharepointToolbox.csproj" />
+</Solution>

SharepointToolbox/App.xaml

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+<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>

SharepointToolbox/App.xaml.cs

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+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Serilog;
+using System.Windows;
+
+namespace SharepointToolbox;
+
+/// <summary>
+/// Interaction logic for App.xaml
+/// </summary>
+public partial class App : Application
+{
+    [STAThread]
+    public static void Main(string[] args)
+    {
+        using IHost host = Host.CreateDefaultBuilder(args)
+            .UseSerilog((ctx, cfg) => cfg
+                .WriteTo.File(
+                    System.IO.Path.Combine(
+                        Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
+                        "SharepointToolbox", "logs", "app-.log"),
+                    rollingInterval: RollingInterval.Day,
+                    retainedFileCountLimit: 30))
+            .ConfigureServices(RegisterServices)
+            .Build();
+
+        host.Start();
+        App app = new();
+        app.InitializeComponent();
+        app.MainWindow = host.Services.GetRequiredService<MainWindow>();
+        app.MainWindow.Visibility = Visibility.Visible;
+        app.Run();
+    }
+
+    private static void RegisterServices(HostBuilderContext ctx, IServiceCollection services)
+    {
+        // Placeholder — services registered in subsequent plans
+        services.AddSingleton<MainWindow>();
+    }
+}

SharepointToolbox/MainWindow.xaml

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+<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>

SharepointToolbox/MainWindow.xaml.cs

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+using System.Text;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Navigation;
+using System.Windows.Shapes;
+
+namespace SharepointToolbox;
+
+/// <summary>
+/// Interaction logic for MainWindow.xaml
+/// </summary>
+public partial class MainWindow : Window
+{
+    public MainWindow()
+    {
+        InitializeComponent();
+    }
+}

SharepointToolbox/SharepointToolbox.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <TargetFramework>net10.0-windows</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <UseWPF>true</UseWPF>
+    <PublishTrimmed>false</PublishTrimmed>
+    <StartupObject>SharepointToolbox.App</StartupObject>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ApplicationDefinition Remove="App.xaml" />
+    <Page Include="App.xaml" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.2" />
+    <PackageReference Include="Microsoft.Extensions.Hosting" Version="10.0.0" />
+    <PackageReference Include="Microsoft.Identity.Client" Version="4.83.3" />
+    <PackageReference Include="Microsoft.Identity.Client.Broker" Version="4.82.1" />
+    <PackageReference Include="Microsoft.Identity.Client.Extensions.Msal" Version="4.83.3" />
+    <PackageReference Include="PnP.Framework" Version="1.18.0" />
+    <PackageReference Include="Serilog" Version="4.3.1" />
+    <PackageReference Include="Serilog.Extensions.Hosting" Version="10.0.0" />
+    <PackageReference Include="Serilog.Sinks.File" Version="7.0.0" />
+  </ItemGroup>
+
+</Project>