fix(ui): EDIT label is white in both states

The armed state was fixed to on-accent last build, but the resting state kept on-surface-variant
(#94a3b8) — so with EDIT off, which is its normal state, the label was grey on the dark bar. The
label is white always now; only the fill changes (neutral → blue). The redundant foreground setter
is gone, and UiShellTests asserts the resting colour rather than the trigger.

Controls/TopBar.xaml

@@ -59,7 +59,7 @@
                  looked pressed. -->
             <ToggleButton IsChecked="{Binding EditingActive, Mode=TwoWay}" Content="EDIT"
                           Cursor="Hand" Height="32" Padding="14,0" Margin="0,0,24,0" VerticalAlignment="Center"
-                          FontWeight="Bold" FontSize="12" Foreground="{StaticResource Brush.OnSurfaceVariant}" BorderThickness="0">
+                          FontWeight="Bold" FontSize="12" Foreground="{StaticResource Brush.OnAccent}" BorderThickness="0">
                 <ToggleButton.Template>
                     <ControlTemplate TargetType="ToggleButton">
                         <Border x:Name="EditBody" Background="{StaticResource Brush.SurfaceContainerHigh}" CornerRadius="4" Padding="{TemplateBinding Padding}">
@@ -68,7 +68,6 @@
                         <ControlTemplate.Triggers>
                             <Trigger Property="IsChecked" Value="True">
                                 <Setter TargetName="EditBody" Property="Background" Value="{StaticResource Brush.Tertiary}"/>
-                                <Setter Property="Foreground" Value="{StaticResource Brush.OnAccent}"/>
                             </Trigger>
                         </ControlTemplate.Triggers>
                     </ControlTemplate>