fix(installer,worker): service hosting, dark theme, uninstall polish

Worker:
- Wire UseWindowsService + Microsoft.Extensions.Hosting.WindowsServices so
  SCM's Service Control Protocol handshake succeeds. Previously the binary
  exited immediately under sc start, leaving the service registered but
  never running.

Installer:
- Pin SDK to .NET 9 (global.json) — SDK 10 dropped win-arm from its RID
  graph, breaking restore of the WPF project; .NET 9 keeps win-arm AND
  understands the .slnx solution format.
- Force SelfContained=true and default RID=win-x64 when PublishSingleFile
  is set, so Rider Publish and CLI produce the same bundle.
- Dark theme: set Background/Foreground explicitly on WizardWindow and
  SettingsWindow roots (WPF implicit styles don't cascade to derived
  Window types). Custom ComboBox template + ComboBoxItem style so
  dropdowns honour the dark palette instead of system defaults.
- Throttle download progress to one report per MB and overwrite the same
  UI line (\r prefix marker) instead of appending per chunk.
- Register ClaudeDo in HKLM\...\Uninstall so it appears in Apps & Features.
  Copy installer into InstallDir\uninstaller\ for the UninstallString, and
  schedule a cmd.exe trampoline to handle the self-delete case when
  Apps & Features launches the copy from inside the install dir.
- Treat sc.exe stop exit 1062 (ERROR_SERVICE_NOT_ACTIVE) as success.
- Delete the uninstall registry key during UninstallRunner.

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

src/ClaudeDo.Installer/Pages/InstallPage/InstallPageViewModel.cs

@@ -54,6 +54,7 @@ public partial class InstallPageViewModel : ObservableObject, IInstallerPage
             Steps.Add(new StepViewModel("Initialize Database"));
             Steps.Add(new StepViewModel("Register Windows Service"));
             Steps.Add(new StepViewModel("Create Shortcuts"));
+            Steps.Add(new StepViewModel("Register in Add/Remove Programs"));
             Steps.Add(new StepViewModel("Write Install Manifest"));
         }
         return Task.CompletedTask;
@@ -82,7 +83,21 @@ public partial class InstallPageViewModel : ObservableObject, IInstallerPage
 
             step.Status = p.Status;
             if (p.Message is not null)
-                step.Messages.Add(p.Message);
+            {
+                // Messages starting with "\r" overwrite the previous line (live progress).
+                if (p.Message.StartsWith('\r'))
+                {
+                    var line = p.Message[1..];
+                    if (step.Messages.Count > 0 && step.Messages[^1].StartsWith("  "))
+                        step.Messages[^1] = line;
+                    else
+                        step.Messages.Add(line);
+                }
+                else
+                {
+                    step.Messages.Add(p.Message);
+                }
+            }
 
             if (p.Status is StepStatus.Running && !step.IsExpanded)
                 step.IsExpanded = true;