fix: shrink test question heading further to h5

Previous h3/text-base was still too large; dropped to h5/text-sm.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/pages/Testen.jsx

@@ -375,7 +375,7 @@ const Testen = () => {
               <div className="flex items-center gap-2 mb-4">
                 <Tag variant="accent" className="text-xs">{q.topicLabel}</Tag>
               </div>
-              <h3 className="text-base font-bold leading-snug">{q.question}</h3>
+              <h5 className="text-sm font-bold leading-snug">{q.question}</h5>
             </Card>
 
             {/* Options */}