fix: show short video durations accurately

services/db.ts

@@ -59,9 +59,14 @@ const toAttachment = (asset: ApiAsset): Attachment => ({
 });
 
 const toDuration = (seconds: number | null) => {
-  if (!seconds) return '—';
-  const minutes = Math.round(seconds / 60);
-  return minutes >= 60 ? `${Math.floor(minutes / 60)}h ${minutes % 60}m` : `${minutes}m`;
+  if (!seconds || seconds < 1) return '—';
+  const totalSeconds = Math.round(seconds);
+  const hours = Math.floor(totalSeconds / 3600);
+  const minutes = Math.floor((totalSeconds % 3600) / 60);
+  const remainingSeconds = totalSeconds % 60;
+  if (hours) return `${hours}h ${String(minutes).padStart(2, '0')}min`;
+  if (minutes) return `${minutes}min`;
+  return `${remainingSeconds}s`;
 };
 
 const toCourseDuration = (lessons: ApiCourse['lessons']) => {