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.Ui/ViewModels/IslandsShellViewModel.cs

@@ -31,6 +31,7 @@ public sealed partial class IslandsShellViewModel : ViewModelBase
 
     private readonly UpdateCheckService _updateCheck = null!;
     private readonly InstallerLocator _installerLocator = null!;
+    private readonly WorkerLocator _workerLocator = null!;
     private readonly IDbContextFactory<ClaudeDoDbContext>? _dbFactory;
     private readonly Func<WorktreesOverviewModalViewModel> _worktreesOverviewVmFactory = () => null!;
     private readonly Func<MergeModalViewModel> _mergeVmFactory = () => null!;
@@ -170,6 +171,7 @@ public sealed partial class IslandsShellViewModel : ViewModelBase
         WorkerClient worker,
         UpdateCheckService updateCheck,
         InstallerLocator installerLocator,
+        WorkerLocator workerLocator,
         IDbContextFactory<ClaudeDoDbContext> dbFactory,
         Func<WorktreesOverviewModalViewModel> worktreesOverviewVmFactory,
         Func<MergeModalViewModel> mergeVmFactory,
@@ -178,6 +180,7 @@ public sealed partial class IslandsShellViewModel : ViewModelBase
         Lists = lists; Tasks = tasks; Details = details; Worker = worker;
         _updateCheck = updateCheck;
         _installerLocator = installerLocator;
+        _workerLocator = workerLocator;
         _dbFactory = dbFactory;
         _worktreesOverviewVmFactory = worktreesOverviewVmFactory;
         _mergeVmFactory = mergeVmFactory;
@@ -218,6 +221,7 @@ public sealed partial class IslandsShellViewModel : ViewModelBase
         _primeStatusTimer.Elapsed += (_, _) =>
             Avalonia.Threading.Dispatcher.UIThread.Post(() => PrimeStatus = null);
         _ = Lists.LoadAsync();
+        _ = EnsureWorkerRunningAsync();
         _updateCheck.PropertyChanged += (_, e) =>
         {
             if (e.PropertyName == nameof(UpdateCheckService.LastCheckStatus))
@@ -301,43 +305,58 @@ public sealed partial class IslandsShellViewModel : ViewModelBase
 
     [ObservableProperty] private string? _restartWorkerStatus;
 
+    private bool _ensureRunningAttempted;
+
+    private async Task EnsureWorkerRunningAsync()
+    {
+        if (_ensureRunningAttempted) return;
+        _ensureRunningAttempted = true;
+        await Task.Delay(TimeSpan.FromSeconds(4));
+        if (Worker?.IsConnected == true) return;
+        var exe = _workerLocator.Find();
+        if (exe is null) return;
+        try { System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(exe) { UseShellExecute = true }); }
+        catch { /* logon task is the primary mechanism; this is a convenience */ }
+    }
+
     [RelayCommand]
     private async Task RestartWorkerAsync()
     {
-        if (!OperatingSystem.IsWindows())
-        {
-            await FlashRestartStatusAsync("Service control is Windows-only.");
-            return;
-        }
-
         RestartWorkerStatus = "Restarting worker…";
         try
         {
             await Task.Run(RestartWorkerService);
             await FlashRestartStatusAsync("Worker restarted.");
         }
-        catch (InvalidOperationException)
-        {
-            // ServiceController throws this when the service is not installed.
-            await FlashRestartStatusAsync("ClaudeDoWorker service is not installed.");
-        }
         catch (Exception ex)
         {
             await FlashRestartStatusAsync($"Restart failed: {ex.Message}");
         }
     }
 
-    [System.Runtime.Versioning.SupportedOSPlatform("windows")]
-    private static void RestartWorkerService()
+    private void RestartWorkerService()
     {
-        using var sc = new System.ServiceProcess.ServiceController("ClaudeDoWorker");
-        if (sc.Status != System.ServiceProcess.ServiceControllerStatus.Stopped)
+        var exe = _workerLocator.Find();
+        if (exe is null) throw new InvalidOperationException("Worker executable not found.");
+
+        // Only kill the worker belonging to THIS installation — not any other
+        // ClaudeDo.Worker on the machine (e.g. a second install).
+        var exeFull = System.IO.Path.GetFullPath(exe);
+        foreach (var p in System.Diagnostics.Process.GetProcessesByName("ClaudeDo.Worker"))
         {
-            sc.Stop();
-            sc.WaitForStatus(System.ServiceProcess.ServiceControllerStatus.Stopped, TimeSpan.FromSeconds(20));
+            try
+            {
+                var path = p.MainModule?.FileName;
+                if (path is not null &&
+                    !string.Equals(System.IO.Path.GetFullPath(path), exeFull, StringComparison.OrdinalIgnoreCase))
+                    continue;
+                p.Kill(entireProcessTree: true);
+                p.WaitForExit(10000);
+            }
+            catch { /* may have exited or be inaccessible */ }
+            finally { p.Dispose(); }
         }
-        sc.Start();
-        sc.WaitForStatus(System.ServiceProcess.ServiceControllerStatus.Running, TimeSpan.FromSeconds(20));
+        System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(exe) { UseShellExecute = true });
     }
 
     private async Task FlashRestartStatusAsync(string text)