ISO toggle: square corners to match the rest of the button family

Wd.Button.IsoToggle was the only button in the GUI using CornerRadius=999
(full pill). It read as a different control type from the toolbar buttons
around it (Enable all, Refresh, Presets, Stop all, Mute, Cam, Leave —
all Radius.M). The pill shape was meant to make the LIVE state visually
distinct, but the status-coded fill (cyan/coral/amber) already carries
that signal — the geometry was double-duty.

Swap the IsoToggle's CornerRadius from 999 to Radius.M so every button
in the app shares the same shape language. Status read remains via the
fill color.

src/TeamsISO.App/Themes/WildDragonTheme.xaml

@@ -319,7 +319,11 @@
         </Setter>
     </Style>
 
-    <!-- ISO toggle: pill, status-coded -->
+    <!-- ISO toggle: rounded-rect (Radius.M) to match the rest of the button
+         family, status-coded background (LIVE cyan / ERROR coral / NO SIGNAL
+         amber). Previously a full pill (CornerRadius=999); pill made the LIVE
+         indicator visually distinct from the toolbar buttons in a way that
+         read as "different control type" rather than "different state". -->
     <Style x:Key="Wd.Button.IsoToggle" TargetType="Button">
         <Setter Property="FontFamily" Value="{StaticResource Wd.Font.Sans}"/>
         <Setter Property="FontSize" Value="11"/>
@@ -340,7 +344,7 @@
                             Background="{TemplateBinding Background}"
                             BorderBrush="{TemplateBinding BorderBrush}"
                             BorderThickness="{TemplateBinding BorderThickness}"
-                            CornerRadius="999">
+                            CornerRadius="{StaticResource Radius.M}">
                         <ContentPresenter HorizontalAlignment="Center"
                                           VerticalAlignment="Center"
                                           Margin="{TemplateBinding Padding}"/>