fix(settings): the App Settings panel scrolls — the lower options were clipped off-screen

The shell is MaxHeight 700 and the settings panel had grown past it with no ScrollViewer,
so everything below roughly the transition section was unreachable. That is why 'Tablet
(Horizontal Rectangle)' existed in the XAML and in the model but never appeared in the app:
the shape control itself was cut off, not the option.

Panel row is now * with an Auto ScrollViewer, so every section is reachable and the next
one added cannot silently fall off the bottom.

Controls/OverlayHost.xaml

@@ -21,7 +21,7 @@
                 <Grid>
                     <Grid.RowDefinitions>
                         <RowDefinition Height="Auto"/>
-                        <RowDefinition Height="Auto"/>
+                        <RowDefinition Height="*"/>
                     </Grid.RowDefinitions>
 
                     <!-- Header -->
@@ -37,9 +37,14 @@
 
                     <!-- App Settings: broadcast fields live in the preview's
                          Text pull-out now — this panel keeps app-level prefs only.
-                         (Currently empty; the overlay shell stays for future use.) -->
-                    <StackPanel Grid.Row="1" Margin="0,8,0,0"
-                                Visibility="{Binding IsSettingsOpen, Converter={StaticResource BoolToVis}}">
+                         ⛔ The ScrollViewer is load-bearing: the shell is MaxHeight 700 and the
+                         panel has more sections than that (Recordings, Brand logo, Preview,
+                         transitions, Zoom box, Developer), so without it the lower options were
+                         clipped off-screen — which is how "Tablet (Horizontal Rectangle)" existed
+                         in the XAML yet never appeared in the app (2026-11-01). -->
+                    <ScrollViewer Grid.Row="1" VerticalScrollBarVisibility="Auto"
+                                  Visibility="{Binding IsSettingsOpen, Converter={StaticResource BoolToVis}}">
+                    <StackPanel Margin="0,8,0,0">
 
                         <TextBlock Text="Recordings" Foreground="{StaticResource Brush.OnSurfaceVariant}" FontSize="11" FontWeight="SemiBold" Margin="0,8,0,2"/>
                         <TextBlock Text="Default location" Foreground="{StaticResource Brush.OnSurfaceVariant}" FontSize="11" Margin="10,0,0,2"/>
@@ -128,6 +133,7 @@
                              this inside #if DEBUG. Never put content here directly. -->
                         <StackPanel x:Name="DeveloperPanelHost"/>
                     </StackPanel>
+                    </ScrollViewer>
 
                     <!-- Report Bug -->
                     <StackPanel Grid.Row="1" Margin="0,16,0,0"