feat: add QuestionMedia with DOMPurify SVG sanitization

frontend/src/components/QuestionMedia.tsx

@@ -0,0 +1,53 @@
+import DOMPurify from 'dompurify'
+import { highlightCode } from '../utils/latex'
+import type { Question } from '../types'
+
+interface Props {
+  q: Question
+}
+
+export default function QuestionMedia({ q }: Props) {
+  return (
+    <>
+      {q.image && (
+        <figure className="q-media">
+          <img src={q.image.src} alt={q.image.alt ?? ''} />
+          {q.image.caption && (
+            <figcaption className="q-media-caption">{q.image.caption}</figcaption>
+          )}
+        </figure>
+      )}
+      {q.audio && (
+        <div className="q-audio">
+          <audio controls src={q.audio.src}>Your browser does not support audio.</audio>
+        </div>
+      )}
+      {q.code && (
+        // highlightCode runs escapeHtml on the source first — output is safe
+        <pre
+          className="q-code"
+          dangerouslySetInnerHTML={{ __html: highlightCode(q.code.content, q.code.language) }}
+        />
+      )}
+      {q.table && (
+        <table className="q-table">
+          <thead>
+            <tr>{q.table.headers.map((h, i) => <th key={i}>{h}</th>)}</tr>
+          </thead>
+          <tbody>
+            {q.table.rows.map((row, i) => (
+              <tr key={i}>{row.map((cell, j) => <td key={j}>{cell}</td>)}</tr>
+            ))}
+          </tbody>
+        </table>
+      )}
+      {q.svg && (
+        // SVG is user-provided — sanitize with DOMPurify before rendering
+        <div
+          className="q-media"
+          dangerouslySetInnerHTML={{ __html: DOMPurify.sanitize(q.svg) }}
+        />
+      )}
+    </>
+  )
+}