feat(installer): add Stop/StartServiceStep sc.exe wrappers

src/ClaudeDo.Installer/Steps/StartServiceStep.cs

@@ -0,0 +1,27 @@
+using ClaudeDo.Installer.Core;
+
+namespace ClaudeDo.Installer.Steps;
+
+public sealed class StartServiceStep : IInstallStep
+{
+    private const string ServiceName = StopServiceStep.ServiceName;
+
+    public string Name => "Start Worker Service";
+
+    public async Task<StepResult> ExecuteAsync(InstallContext ctx, IProgress<string> progress, CancellationToken ct)
+    {
+        progress.Report($"Starting {ServiceName}...");
+
+        var (exit, output) = await ProcessRunner.RunAsync("sc.exe", $"start {ServiceName}", null, progress, ct);
+        if (exit == 0) return StepResult.Ok();
+
+        // Exit 1056 = already running — that's fine too.
+        if (output.Contains("1056", StringComparison.OrdinalIgnoreCase))
+        {
+            progress.Report("Service was already running.");
+            return StepResult.Ok();
+        }
+
+        return StepResult.Fail($"sc.exe start failed with exit code {exit}");
+    }
+}