style: align settings header with sidebar header bar

- Change settings-header to settings-header-bar class
- Match styling of sidebar-header-bar (background, border, padding)
- Reduce title font size to match sidebar style
- Adjust padding and spacing for consistent visual alignment
- Settings header now appears on same visual line as sidebar buttons

src/components/Settings.tsx

@@ -24,7 +24,7 @@ const Settings: React.FC<SettingsProps> = ({ settings, onSave, onClose, isSaving
 
   return (
     <div className="settings-view">
-      <div className="settings-header">
+      <div className="settings-header-bar">
         <h2>Settings</h2>
         <IconButton
           icon={faTimes}