feat(worker): run worker as per-user logon task instead of Windows service

A LocalSystem Windows service can't see the logged-in user's Claude CLI
authentication, so the worker now runs as the current user via a hidden
per-user logon Scheduled Task with restart-on-failure.

- Worker is WinExe (no console window) with a Serilog rolling file sink and
  a single-instance mutex so the logon task, app ensure-running, and Restart
  button can't fight over the SignalR port.
- Installer replaces the service steps (register/start/stop) with autostart
  task steps, migrates the legacy ClaudeDoWorker service away on update, and
  removes the task on uninstall. ServicePage drops the service-account UI.
- UI gains a WorkerLocator; the app ensures the worker is running at startup
  and the Restart button kills+relaunches this install's worker process.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/ClaudeDo.Worker/ClaudeDo.Worker.csproj

@@ -10,7 +10,8 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="Microsoft.Extensions.Hosting" Version="8.0.1" />
-    <PackageReference Include="Microsoft.Extensions.Hosting.WindowsServices" Version="8.0.1" />
+    <PackageReference Include="Serilog.AspNetCore" Version="8.0.3" />
+    <PackageReference Include="Serilog.Sinks.File" Version="6.0.0" />
     <PackageReference Include="ModelContextProtocol" Version="1.2.0" />
     <PackageReference Include="ModelContextProtocol.AspNetCore" Version="1.2.0" />
   </ItemGroup>
@@ -23,6 +24,7 @@
 
   <PropertyGroup>
     <TargetFramework>net8.0</TargetFramework>
+    <OutputType>WinExe</OutputType>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>