temp: visible debug banner for coverImage

src/app/(student)/courses/[slug]/lessons/[lessonId]/page.tsx

@@ -127,7 +127,7 @@ export default async function LessonPage({ params }: Props) {
         <div className="mb-8">
           <KinescopePlayer videoId={lesson.kinescopeId} poster={lesson.coverImage ?? undefined} />
           {/* DEBUG: remove after fix */}
-          {isAdmin && <p style={{fontSize:11,color:"gray",marginTop:4}}>coverImage: {lesson.coverImage ?? "NULL"}</p>}
+          <div style={{background:"red",color:"white",padding:"4px 8px",fontSize:12}}>DEBUG coverImage: {String(lesson.coverImage ?? "NULL")} | isAdmin: {String(isAdmin)}</div>
         </div>
       )}