chore(scaffold): add solution skeleton for App, Ui, Data, Worker and tests

Create .slnx with five projects, wire references (App->Ui->Data,
Worker->Data, Tests->Worker+Data), install Avalonia/MVVM/SignalR.Client/
Sqlite/Hosting packages, and add schema.sql per docs/plan.md.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/ClaudeDo.App/App.axaml

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+<Application xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="ClaudeDo.App.App"
+             xmlns:local="using:ClaudeDo.App"
+             RequestedThemeVariant="Default">
+             <!-- "Default" ThemeVariant follows system theme variant. "Dark" or "Light" are other available options. -->
+
+    <Application.DataTemplates>
+        <local:ViewLocator/>
+    </Application.DataTemplates>
+  
+    <Application.Styles>
+        <FluentTheme />
+    </Application.Styles>
+</Application>

src/ClaudeDo.App/App.axaml.cs

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+using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Data.Core;
+using Avalonia.Data.Core.Plugins;
+using System.Linq;
+using Avalonia.Markup.Xaml;
+using ClaudeDo.Ui.ViewModels;
+using ClaudeDo.Ui.Views;
+
+namespace ClaudeDo.App;
+
+public partial class App : Application
+{
+    public override void Initialize()
+    {
+        AvaloniaXamlLoader.Load(this);
+    }
+
+    public override void OnFrameworkInitializationCompleted()
+    {
+        if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+        {
+            desktop.MainWindow = new MainWindow
+            {
+                DataContext = new MainWindowViewModel(),
+            };
+        }
+
+        base.OnFrameworkInitializationCompleted();
+    }
+}

src/ClaudeDo.App/ClaudeDo.App.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ApplicationManifest>app.manifest</ApplicationManifest>
+    <AvaloniaUseCompiledBindingsByDefault>true</AvaloniaUseCompiledBindingsByDefault>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Folder Include="Models\" />
+    <AvaloniaResource Include="Assets\**" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Avalonia" Version="12.0.0" />
+    <PackageReference Include="Avalonia.Desktop" Version="12.0.0" />
+    <PackageReference Include="Avalonia.Themes.Fluent" Version="12.0.0" />
+    <PackageReference Include="Avalonia.Fonts.Inter" Version="12.0.0" />
+    <PackageReference Include="AvaloniaUI.DiagnosticsSupport" Version="2.2.0">
+      <IncludeAssets Condition="'$(Configuration)' != 'Debug'">None</IncludeAssets>
+      <PrivateAssets Condition="'$(Configuration)' != 'Debug'">All</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\ClaudeDo.Ui\ClaudeDo.Ui.csproj" />
+  </ItemGroup>
+</Project>

src/ClaudeDo.App/Program.cs

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+using Avalonia;
+using System;
+
+namespace ClaudeDo.App;
+
+sealed class Program
+{
+    // Initialization code. Don't use any Avalonia, third-party APIs or any
+    // SynchronizationContext-reliant code before AppMain is called: things aren't initialized
+    // yet and stuff might break.
+    [STAThread]
+    public static void Main(string[] args) => BuildAvaloniaApp()
+        .StartWithClassicDesktopLifetime(args);
+
+    // Avalonia configuration, don't remove; also used by visual designer.
+    public static AppBuilder BuildAvaloniaApp()
+        => AppBuilder.Configure<App>()
+            .UsePlatformDetect()
+#if DEBUG
+            .WithDeveloperTools()
+#endif
+            .WithInterFont()
+            .LogToTrace();
+}

src/ClaudeDo.App/ViewLocator.cs

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+using System;
+using System.Diagnostics.CodeAnalysis;
+using Avalonia.Controls;
+using Avalonia.Controls.Templates;
+using ClaudeDo.Ui.ViewModels;
+
+namespace ClaudeDo.App;
+
+/// <summary>
+/// Given a view model, returns the corresponding view if possible.
+/// </summary>
+[RequiresUnreferencedCode(
+    "Default implementation of ViewLocator involves reflection which may be trimmed away.",
+    Url = "https://docs.avaloniaui.net/docs/concepts/view-locator")]
+public class ViewLocator : IDataTemplate
+{
+    public Control? Build(object? param)
+    {
+        if (param is null)
+            return null;
+        
+        var name = param.GetType().FullName!.Replace("ViewModel", "View", StringComparison.Ordinal);
+        var type = typeof(ViewModelBase).Assembly.GetType(name);
+
+        if (type != null)
+        {
+            return (Control)Activator.CreateInstance(type)!;
+        }
+        
+        return new TextBlock { Text = "Not Found: " + name };
+    }
+
+    public bool Match(object? data)
+    {
+        return data is ViewModelBase;
+    }
+}

src/ClaudeDo.App/app.manifest

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+<?xml version="1.0" encoding="utf-8"?>
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
+  <!-- This manifest is used on Windows only.
+       Don't remove it as it might cause problems with window transparency and embedded controls.
+       For more details visit https://learn.microsoft.com/en-us/windows/win32/sbscs/application-manifests -->
+  <assemblyIdentity version="1.0.0.0" name="ClaudeDo.App.Desktop"/>
+
+  <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
+    <application>
+      <!-- A list of the Windows versions that this application has been tested on
+           and is designed to work with. Uncomment the appropriate elements
+           and Windows will automatically select the most compatible environment. -->
+
+      <!-- Windows 10 -->
+      <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}" />
+    </application>
+  </compatibility>
+</assembly>