fix(ui): unify settings top panel surface

src/components/SettingsView.tsx

@@ -740,10 +740,9 @@ runEngineChecks(false);
 
   return (
     <div className="settings-view flex-1 flex flex-col relative h-full overflow-hidden">
-        <WindowDragRegion />
-
         {/* SwiftUI SettingsPaneContainer-style horizontal tab strip */}
         <div className="settings-toolbar">
+          <WindowDragRegion />
           <div className={`settings-tab-strip flex items-stretch gap-1 ${
             isSidebarOnRight ? 'settings-tab-strip--sidebar-right' : ''
           }`}>

src/index.css

@@ -1245,7 +1245,7 @@ html[data-list-density="relaxed"] {
   .app-sidebar-shell {
     padding-block: 10px;
     padding-inline-start: 10px;
-    background: transparent;
+    background: hsl(var(--statusbar-bg));
   }
 
   .app-sidebar-shell--left {
@@ -1592,6 +1592,7 @@ html[data-list-density="relaxed"] {
 
   .settings-toolbar {
     border-bottom: 1px solid hsl(var(--border-color));
+    background: hsl(var(--statusbar-bg));
   }
 
   .settings-tab-strip {