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.App/Program.cs

@@ -83,6 +83,7 @@ sealed class Program
         sc.AddSingleton<HttpClient>(_ => new HttpClient { Timeout = TimeSpan.FromSeconds(10) });
         sc.AddSingleton<IReleaseClient>(sp => new ReleaseClient(sp.GetRequiredService<HttpClient>()));
         sc.AddSingleton<InstallerLocator>();
+        sc.AddSingleton<WorkerLocator>();
         sc.AddSingleton(sp =>
         {
             var releases = sp.GetRequiredService<IReleaseClient>();