Make URLs in homework answers and feedback clickable

Apply linkify() to student submission text (curator review page + student
cabinet: reviewed/approved/pending) and to curator feedback text, so pasted
links (e.g. Yandex.Disk) render as clickable anchors.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/curator/homework/[submissionId]/page.tsx

@@ -1,6 +1,7 @@
 import { prisma } from "@/lib/prisma";
 import { notFound } from "next/navigation";
 import Link from "next/link";
+import { linkify } from "@/lib/linkify";
 import { FeedbackForm } from "./feedback-form";
 import { ContentTabs } from "./content-tabs";
 import { DeleteSubmissionButton } from "./delete-button";
@@ -151,7 +152,7 @@ export default async function SubmissionPage({ params }: Props) {
             className="px-4 py-3 text-sm whitespace-pre-wrap"
             style={{ border: "2px solid var(--border)" }}
           >
-            {submission.text}
+            {linkify(submission.text)}
           </div>
         ) : (
           <p className="text-sm italic" style={{ color: "var(--muted-foreground)" }}>