[GUI] split shared theme into resource dictionaries (#669)

src/SharpEmu.GUI/Themes/Styles/Surfaces.axaml

@@ -0,0 +1,55 @@
+<!--
+Copyright (C) 2026 SharpEmu Emulator Project
+SPDX-License-Identifier: GPL-2.0-or-later
+Shared card, badge, hint and cover surfaces.
+-->
+
+<Styles xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+  <Style Selector="Border.card">
+    <Setter Property="Background" Value="{StaticResource CardBrush}" />
+    <Setter Property="BorderBrush" Value="{StaticResource CardBorderBrush}" />
+    <Setter Property="BorderThickness" Value="1" />
+    <Setter Property="CornerRadius" Value="12" />
+    <Setter Property="Padding" Value="16" />
+  </Style>
+
+  <Style Selector="Border.pill">
+    <Setter Property="Background" Value="{StaticResource ElevatedBrush}" />
+    <Setter Property="CornerRadius" Value="999" />
+    <Setter Property="Padding" Value="10,3" />
+  </Style>
+
+  <!-- Session status/hotkey badges: the title-id pill geometry with a
+       tinted fill so state (RUNNING) and keys (F11) read at a glance. -->
+  <Style Selector="Border.badge">
+    <Setter Property="CornerRadius" Value="999" />
+    <Setter Property="Padding" Value="8,2" />
+    <Setter Property="BorderThickness" Value="1" />
+  </Style>
+  <Style Selector="Border.badge.running">
+    <Setter Property="Background" Value="#1E46C46B" />
+    <Setter Property="BorderBrush" Value="#5546C46B" />
+  </Style>
+  <Style Selector="Border.badge.key">
+    <Setter Property="Background" Value="#1E58A6FF" />
+    <Setter Property="BorderBrush" Value="#5558A6FF" />
+  </Style>
+
+  <!-- Gamepad shoulder-button hint chip (LB/RB, L1/R1). -->
+  <Style Selector="Border.padHint">
+    <Setter Property="Background" Value="{StaticResource ElevatedBrush}" />
+    <Setter Property="CornerRadius" Value="6" />
+    <Setter Property="Padding" Value="8,3" />
+  </Style>
+
+  <Style Selector="Border.coverShadow">
+    <Setter Property="CornerRadius" Value="10" />
+    <Setter Property="BoxShadow" Value="0 6 14 0 #55000000" />
+  </Style>
+  <Style Selector="Border.coverClip">
+    <Setter Property="CornerRadius" Value="10" />
+    <Setter Property="ClipToBounds" Value="True" />
+    <Setter Property="Background" Value="{StaticResource ElevatedBrush}" />
+  </Style>
+</Styles>