feat: replace inline formatDuration function with imported utility for better code reuse

src/pages/SoundboardPage.tsx

@@ -6,6 +6,7 @@ import { toast } from 'sonner';
 import { apiService } from '@/services/api';
 import { AddUrlDialog } from '@/components/AddUrlDialog';
 import { useAddUrlShortcut } from '@/hooks/use-keyboard-shortcuts';
+import { formatDuration } from '@/lib/format-duration';
 
 interface Sound {
   id: number;
@@ -29,12 +30,6 @@ const SoundCard: React.FC<SoundCardProps> = ({ sound, onPlay, isPlaying }) => {
     onPlay(sound.id);
   };
 
-  const formatDuration = (seconds: number) => {
-    const mins = Math.floor(seconds / 60);
-    const secs = seconds % 60;
-    return `${mins}:${secs.toString().padStart(2, '0')}`;
-  };
-
   return (
     <Card className="transition-all duration-200 hover:shadow-lg cursor-pointer group">
       <CardHeader className="pb-3">