Add homework system (admin, student, curator)

Admin:
- HomeworkEditor in lesson page: create/update/delete assignment description

Student:
- HomeworkSection in lesson page: view assignment, submit text + files
- Resubmission allowed until curator gives feedback
- Shows feedback from curator with date and name

Curator:
- New layout with Second Brain dark sidebar (replaces green theme)
- /curator/dashboard: stats cards (pending, total, reviewed this week)
- /curator/homework: list of all submissions, pending highlighted
- /curator/homework/[id]: review submission, write feedback, redirect after send

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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

@@ -0,0 +1,132 @@
+import { prisma } from "@/lib/prisma";
+import { notFound } from "next/navigation";
+import Link from "next/link";
+import { FeedbackForm } from "./feedback-form";
+
+interface Props {
+  params: Promise<{ submissionId: string }>;
+}
+
+function formatSize(bytes: number) {
+  if (bytes < 1024) return `${bytes} Б`;
+  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(0)} КБ`;
+  return `${(bytes / 1024 / 1024).toFixed(1)} МБ`;
+}
+
+export default async function SubmissionPage({ params }: Props) {
+  const { submissionId } = await params;
+
+  const submission = await prisma.homeworkSubmission.findUnique({
+    where: { id: submissionId },
+    include: {
+      user: { select: { name: true, email: true } },
+      feedbacks: {
+        include: { curator: { select: { name: true } } },
+        orderBy: { createdAt: "desc" },
+      },
+      homework: {
+        include: {
+          lesson: {
+            select: {
+              title: true,
+              module: { select: { title: true, course: { select: { title: true } } } },
+            },
+          },
+        },
+      },
+    },
+  });
+
+  if (!submission) notFound();
+
+  const files = (submission.files as { name: string; url: string; size: number }[]) ?? [];
+  const isReviewed = submission.feedbacks.length > 0;
+
+  return (
+    <div className="p-8 max-w-2xl">
+      <nav className="text-xs mb-6 uppercase tracking-widest" style={{ color: "var(--muted-foreground)" }}>
+        <Link href="/curator/homework" className="hover:underline">ДЗ на проверку</Link>
+        <span className="mx-2">/</span>
+        <span style={{ color: "var(--foreground)" }}>{submission.user.name}</span>
+      </nav>
+
+      {/* Meta */}
+      <div className="mb-6">
+        <h1 className="text-xl font-bold">{submission.homework.lesson.title}</h1>
+        <p className="text-sm mt-1" style={{ color: "var(--muted-foreground)" }}>
+          {submission.homework.lesson.module.course.title} · {submission.homework.lesson.module.title}
+        </p>
+      </div>
+
+      {/* Student info */}
+      <div className="flex items-center justify-between px-4 py-3 mb-6" style={{ border: "2px solid var(--border)", background: "var(--color-surface)" }}>
+        <div>
+          <p className="font-medium text-sm">{submission.user.name}</p>
+          <p className="text-xs" style={{ color: "var(--muted-foreground)" }}>{submission.user.email}</p>
+        </div>
+        <p className="text-xs" style={{ color: "var(--muted-foreground)" }}>
+          Сдано {new Date(submission.submittedAt).toLocaleDateString("ru-RU")}
+        </p>
+      </div>
+
+      {/* Homework description */}
+      <div className="mb-4">
+        <p className="text-xs font-bold uppercase tracking-widest mb-2" style={{ color: "var(--muted-foreground)" }}>Задание</p>
+        <div className="px-4 py-3 text-sm whitespace-pre-wrap" style={{ border: "2px solid var(--border)", background: "var(--color-surface)" }}>
+          {submission.homework.description}
+        </div>
+      </div>
+
+      {/* Student answer */}
+      <div className="mb-4">
+        <p className="text-xs font-bold uppercase tracking-widest mb-2" style={{ color: "var(--muted-foreground)" }}>Ответ студента</p>
+        {submission.text ? (
+          <div className="px-4 py-3 text-sm whitespace-pre-wrap" style={{ border: "2px solid var(--border)" }}>
+            {submission.text}
+          </div>
+        ) : (
+          <p className="text-sm italic" style={{ color: "var(--muted-foreground)" }}>Текст не добавлен</p>
+        )}
+      </div>
+
+      {/* Files */}
+      {files.length > 0 && (
+        <div className="mb-6">
+          <p className="text-xs font-bold uppercase tracking-widest mb-2" style={{ color: "var(--muted-foreground)" }}>Прикреплённые файлы</p>
+          <div className="space-y-1">
+            {files.map((f) => (
+              <a
+                key={f.url}
+                href={f.url}
+                target="_blank"
+                rel="noopener noreferrer"
+                className="flex items-center gap-3 px-3 py-2 text-sm"
+                style={{ border: "2px solid var(--border)" }}
+              >
+                <span>📎</span>
+                <span className="flex-1 underline">{f.name}</span>
+                <span className="text-xs" style={{ color: "var(--muted-foreground)" }}>{formatSize(f.size)}</span>
+              </a>
+            ))}
+          </div>
+        </div>
+      )}
+
+      {/* Existing feedback */}
+      {submission.feedbacks.map((fb) => (
+        <div key={fb.id} className="mb-4 px-4 py-3" style={{ border: "2px solid var(--foreground)", background: "var(--accent)" }}>
+          <div className="flex items-center justify-between mb-1">
+            <p className="text-xs font-bold uppercase tracking-widest">Фидбек</p>
+            <span className="text-xs" style={{ color: "var(--muted-foreground)" }}>
+              {fb.curator.name} · {new Date(fb.createdAt).toLocaleDateString("ru-RU")}
+            </span>
+          </div>
+          <p className="text-sm whitespace-pre-wrap">{fb.text}</p>
+        </div>
+      ))}
+
+      {/* Feedback form */}
+      {!isReviewed && <FeedbackForm submissionId={submissionId} />}
+    </div>
+  );
+}