Controller overlay changed from Window to UserControl

src/Ryujinx/UI/Controls/ControllerOverlay.axaml

@@ -0,0 +1,46 @@
+<UserControl
+    xmlns="https://github.com/avaloniaui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    d:DesignWidth="400"
+    d:DesignHeight="300"
+    x:Class="Ryujinx.Ava.UI.Controls.ControllerOverlay"
+    Focusable="False"
+    IsVisible="False"
+    Name="ControllerOverlayControl">
+    
+    <Border Background="#E0000000" 
+            CornerRadius="12" 
+            Padding="24"
+            BorderBrush="#40FFFFFF"
+            BorderThickness="1">
+        <StackPanel Spacing="16">
+            <StackPanel Orientation="Horizontal" 
+                        HorizontalAlignment="Center"
+                        Spacing="8">
+                <TextBlock Text="🎮" 
+                           FontSize="18" 
+                           VerticalAlignment="Center"/>
+                <TextBlock Text="Controller Bindings" 
+                           FontSize="18" 
+                           FontWeight="Bold" 
+                           Foreground="White"
+                           VerticalAlignment="Center"/>
+            </StackPanel>
+            
+            <StackPanel Name="PlayerBindings" Spacing="10">
+                <!-- Player bindings will be added programmatically -->
+            </StackPanel>
+            
+                         <TextBlock Name="DurationText"
+                        Text="This overlay will disappear in a few seconds" 
+                        FontSize="11" 
+                        Foreground="#AAAAAA"
+                        HorizontalAlignment="Center"
+                        Margin="0,8,0,0"
+                        FontStyle="Italic"/>
+                 </StackPanel>
+     </Border>
+ </UserControl>