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

@@ -6,6 +6,7 @@ import { auth } from "@/lib/auth";
 import { KinescopePlayer } from "@/components/player/kinescope-player";
 import { LessonContent } from "@/components/student/lesson-content";
 import { LessonCompleteButton } from "@/components/student/lesson-complete-button";
+import { HomeworkSection } from "@/components/student/homework-section";
 
 interface Props {
   params: Promise<{ slug: string; lessonId: string }>;
@@ -22,6 +23,7 @@ export default async function LessonPage({ params }: Props) {
       where: { id: lessonId, ...(isAdmin ? {} : { published: true }) },
       include: {
         files: { orderBy: { createdAt: "asc" } },
+        homework: true,
         module: {
           include: {
             course: {
@@ -49,6 +51,14 @@ export default async function LessonPage({ params }: Props) {
       : null,
   ]);
 
+  // Fetch homework submission for this student
+  const homeworkSubmission = lesson?.homework && session && !isAdmin
+    ? await prisma.homeworkSubmission.findFirst({
+        where: { homeworkId: lesson.homework.id, userId: session.user.id },
+        include: { feedbacks: { include: { curator: { select: { name: true } } }, orderBy: { createdAt: "desc" } } },
+      })
+    : null;
+
   if (!lesson || lesson.module.course.slug !== slug) notFound();
 
   const isCompleted = !!progress;
@@ -118,6 +128,24 @@ export default async function LessonPage({ params }: Props) {
         </div>
       )}
 
+      {/* Homework */}
+      {lesson.homework && !isAdmin && (
+        <div className="mb-8">
+          <p className="text-xs font-bold uppercase tracking-widest mb-3" style={{ color: "var(--muted-foreground)" }}>
+            Домашнее задание
+          </p>
+          <HomeworkSection
+            homework={lesson.homework}
+            submission={homeworkSubmission ? {
+              ...homeworkSubmission,
+              files: (homeworkSubmission.files as { name: string; url: string; size: number }[]) ?? [],
+            } : null}
+            slug={slug}
+            lessonId={lessonId}
+          />
+        </div>
+      )}
+
       {/* Complete button + Prev/Next navigation */}
       <div
         className="flex items-center justify-between pt-6 mt-6"