feat: initialize and setup demo.

src/Ursa.Themes.Semi/Controls/EnumSelector.axaml

@@ -0,0 +1,13 @@
+<ResourceDictionary
+    xmlns="https://github.com/avaloniaui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:u="https://irihi.tech/ursa">
+    <!--  Add Resources Here  -->
+    <ControlTheme x:Key="{x:Type u:EnumSelector}" TargetType="u:EnumSelector">
+        <Setter Property="Template">
+            <ControlTemplate TargetType="u:EnumSelector">
+                <ComboBox ItemsSource="{TemplateBinding Values}" SelectedItem="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Value, Mode=TwoWay}" />
+            </ControlTemplate>
+        </Setter>
+    </ControlTheme>
+</ResourceDictionary>

src/Ursa.Themes.Semi/Controls/_index.axaml

@@ -6,6 +6,7 @@
         <ResourceInclude Source="ButtonGroup.axaml" />
         <ResourceInclude Source="Divider.axaml" />
         <ResourceInclude Source="DualBadge.axaml" />
+        <ResourceInclude Source="EnumSelector.axaml" />
         <ResourceInclude Source="IconButton.axaml" />
         <ResourceInclude Source="ImageViewer.axaml" />
         <ResourceInclude Source="IPv4Box.axaml" />