refactor: extract MobileTabs shared component, replace in all 8 tools

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

components/units/MainConverter.tsx

@@ -14,6 +14,7 @@ import {
   type ConversionResult,
 } from '@/lib/units/units';
 import { parseNumberInput, formatNumber, cn } from '@/lib/utils';
+import { MobileTabs } from '@/components/ui/mobile-tabs';
 
 type Tab = 'category' | 'convert';
 
@@ -87,23 +88,11 @@ export default function MainConverter() {
   return (
     <div className="flex flex-col gap-4">
 
-      {/* ── Mobile tab switcher ────────────────────────────────── */}
-      <div className="flex lg:hidden glass rounded-xl p-1 gap-1">
-        {(['category', 'convert'] as Tab[]).map((t) => (
-          <button
-            key={t}
-            onClick={() => setTab(t)}
-            className={cn(
-              'flex-1 py-2.5 rounded-lg text-sm font-medium capitalize transition-all',
-              tab === t
-                ? 'bg-primary text-primary-foreground shadow-sm'
-                : 'text-muted-foreground hover:text-foreground'
-            )}
-          >
-            {t === 'category' ? 'Category' : 'Convert'}
-          </button>
-        ))}
-      </div>
+      <MobileTabs
+        tabs={[{ value: 'category', label: 'Category' }, { value: 'convert', label: 'Convert' }]}
+        active={tab}
+        onChange={(v) => setTab(v as Tab)}
+      />
 
       {/* ── Main layout ────────────────────────────────────────── */}
       <div