fix(ui): match Custom Accent h3 styling to chat settings

- Remove text-xs to use default font size (~14-16px)
- Matches h3 styling in ModeSelectionItem and VoiceDictationToggle
- Ensures visual consistency across all settings sections

ui/desktop/src/components/GooseSidebar/ThemeSelector.tsx

@@ -219,7 +219,7 @@ export function ThemeSelector({
       <div className={cn(!horizontal && 'px-3', 'py-3')}>
         <div className="flex items-center justify-between mb-2">
           <div className="flex-1">
-            <h3 className="text-text-default text-xs">Custom Accent</h3>
+            <h3 className="text-text-default">Custom Accent</h3>
           </div>
           <Switch
             checked={customColorEnabled}