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/Theme/DarkTheme.xaml

@@ -184,6 +184,34 @@
         </Setter>
     </Style>
 
+    <!-- ComboBox toggle button (dropdown arrow chrome) -->
+    <ControlTemplate x:Key="ComboBoxToggleButtonTemplate" TargetType="ToggleButton">
+        <Border x:Name="Bd"
+                Background="{StaticResource IslandBgBrush}"
+                BorderBrush="{StaticResource BorderSubtleBrush}"
+                BorderThickness="1"
+                CornerRadius="4">
+            <Grid>
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition Width="*"/>
+                    <ColumnDefinition Width="20"/>
+                </Grid.ColumnDefinitions>
+                <Path Grid.Column="1"
+                      HorizontalAlignment="Center" VerticalAlignment="Center"
+                      Fill="{StaticResource TextSecondaryBrush}"
+                      Data="M 0 0 L 4 4 L 8 0 Z"/>
+            </Grid>
+        </Border>
+        <ControlTemplate.Triggers>
+            <Trigger Property="IsMouseOver" Value="True">
+                <Setter TargetName="Bd" Property="BorderBrush" Value="{StaticResource AccentBrush}"/>
+            </Trigger>
+            <Trigger Property="IsChecked" Value="True">
+                <Setter TargetName="Bd" Property="BorderBrush" Value="{StaticResource AccentBrush}"/>
+            </Trigger>
+        </ControlTemplate.Triggers>
+    </ControlTemplate>
+
     <!-- ComboBox -->
     <Style TargetType="ComboBox">
         <Setter Property="Background" Value="{StaticResource IslandBgBrush}"/>
@@ -191,6 +219,71 @@
         <Setter Property="BorderBrush" Value="{StaticResource BorderSubtleBrush}"/>
         <Setter Property="BorderThickness" Value="1"/>
         <Setter Property="Padding" Value="8,6"/>
+        <Setter Property="SnapsToDevicePixels" Value="True"/>
+        <Setter Property="Template">
+            <Setter.Value>
+                <ControlTemplate TargetType="ComboBox">
+                    <Grid>
+                        <ToggleButton x:Name="ToggleButton"
+                                      Template="{StaticResource ComboBoxToggleButtonTemplate}"
+                                      Focusable="False"
+                                      IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
+                                      ClickMode="Press"/>
+                        <ContentPresenter x:Name="ContentSite"
+                                          IsHitTestVisible="False"
+                                          Content="{TemplateBinding SelectionBoxItem}"
+                                          ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
+                                          ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
+                                          Margin="{TemplateBinding Padding}"
+                                          VerticalAlignment="Center" HorizontalAlignment="Left"
+                                          TextElement.Foreground="{StaticResource TextPrimaryBrush}"/>
+                        <Popup x:Name="Popup"
+                               Placement="Bottom"
+                               IsOpen="{TemplateBinding IsDropDownOpen}"
+                               AllowsTransparency="True" Focusable="False"
+                               PopupAnimation="Slide">
+                            <Border x:Name="DropDownBorder"
+                                    Background="{StaticResource IslandBgBrush}"
+                                    BorderBrush="{StaticResource BorderSubtleBrush}"
+                                    BorderThickness="1"
+                                    CornerRadius="4"
+                                    MinWidth="{TemplateBinding ActualWidth}"
+                                    MaxHeight="{TemplateBinding MaxDropDownHeight}">
+                                <ScrollViewer SnapsToDevicePixels="True">
+                                    <StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained"/>
+                                </ScrollViewer>
+                            </Border>
+                        </Popup>
+                    </Grid>
+                </ControlTemplate>
+            </Setter.Value>
+        </Setter>
+    </Style>
+
+    <!-- ComboBoxItem — dark dropdown rows -->
+    <Style TargetType="ComboBoxItem">
+        <Setter Property="Background" Value="{StaticResource IslandBgBrush}"/>
+        <Setter Property="Foreground" Value="{StaticResource TextPrimaryBrush}"/>
+        <Setter Property="Padding" Value="8,6"/>
+        <Setter Property="Template">
+            <Setter.Value>
+                <ControlTemplate TargetType="ComboBoxItem">
+                    <Border x:Name="Bd"
+                            Background="{TemplateBinding Background}"
+                            Padding="{TemplateBinding Padding}">
+                        <ContentPresenter/>
+                    </Border>
+                    <ControlTemplate.Triggers>
+                        <Trigger Property="IsHighlighted" Value="True">
+                            <Setter TargetName="Bd" Property="Background" Value="{StaticResource SelectionHoverBrush}"/>
+                        </Trigger>
+                        <Trigger Property="IsSelected" Value="True">
+                            <Setter TargetName="Bd" Property="Background" Value="{StaticResource SelectionBrush}"/>
+                        </Trigger>
+                    </ControlTemplate.Triggers>
+                </ControlTemplate>
+            </Setter.Value>
+        </Setter>
     </Style>
 
     <!-- CheckBox -->