feat(xcui): advance core and editor validation flow

new_editor/ui/themes/editor_shell.xctheme

@@ -1,15 +1,7 @@
 <Theme name="EditorShellTheme">
   <Tokens>
-    <Color name="color.bg.workspace" value="#1C1C1C" />
-    <Color name="color.bg.panel" value="#292929" />
-    <Color name="color.bg.accent" value="#3A3A3A" />
-    <Color name="color.bg.selection" value="#4A4A4A" />
-    <Color name="color.text.primary" value="#EEEEEE" />
-    <Color name="color.text.muted" value="#B0B0B0" />
-    <Spacing name="space.panel" value="12" />
-    <Spacing name="space.shell" value="18" />
-    <Radius name="radius.panel" value="10" />
-    <Radius name="radius.control" value="8" />
+    <Color name="color.bg.workspace" value="#16181C" />
+    <Spacing name="space.shell" value="14" />
   </Tokens>
 
   <Widgets>
@@ -17,16 +9,5 @@
       <Property name="background" value="color.bg.workspace" />
       <Property name="padding" value="space.shell" />
     </Widget>
-
-    <Widget type="Card" style="EditorPanel">
-      <Property name="background" value="color.bg.panel" />
-      <Property name="radius" value="radius.panel" />
-      <Property name="padding" value="space.panel" />
-    </Widget>
-
-    <Widget type="Button" style="EditorChip">
-      <Property name="background" value="color.bg.selection" />
-      <Property name="radius" value="radius.control" />
-    </Widget>
   </Widgets>
 </Theme>

new_editor/ui/views/editor_shell.xcui

@@ -1,8 +1,9 @@
 <View
   name="NewEditorShell"
-  theme="../themes/editor_shell.xctheme">
+  theme="../themes/editor_shell.xctheme"
+  style="EditorWorkspace">
   <Column
-    id="editor-shell-root"
+    id="editor-foundation-root"
     width="fill"
     height="fill" />
 </View>