fix: remove emojis from units tool category list

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/units/MainConverter.tsx

@@ -18,11 +18,6 @@ import { MobileTabs } from '@/components/ui/mobile-tabs';
 
 type Tab = 'category' | 'convert';
 
-const CATEGORY_ICONS: Partial<Record<Measure, string>> = {
-  length: '📏', mass: '⚖️', temperature: '🌡️', speed: '⚡', time: '⏱️',
-  area: '⬛', volume: '🧊', digital: '💾', energy: '⚡', pressure: '🔵',
-  power: '🔆', frequency: '〰️', angle: '📐', current: '⚡', voltage: '🔌',
-};
 
 export default function MainConverter() {
   const [selectedMeasure, setSelectedMeasure] = useState<Measure>('length');
@@ -142,9 +137,6 @@ export default function MainConverter() {
                         : 'border-transparent text-foreground/65 hover:bg-primary/8 hover:text-foreground'
                     )}
                   >
-                    <span className="text-xs leading-none shrink-0 opacity-70">
-                      {CATEGORY_ICONS[measure] ?? '📦'}
-                    </span>
                     <span className="flex-1 text-xs font-mono truncate">{formatMeasureName(measure)}</span>
                     <span
                       className={cn(