Add homework review workflow: statuses, audio, file attachments, tabs

- HomeworkSubmission: add status (PENDING/REVIEWING/APPROVED/REJECTED) + statusAt
- HomeworkFeedback: add files (Json) + audioUrl fields
- Curator detail page: meta table, content tabs, feedback history with audio/files
- FeedbackForm: file upload, audio recorder (Web Audio API + S3), action buttons
- AudioRecorder component: record → preview → upload to S3
- ContentTabs: toggle between homework description and lesson content (TipTap read-only)
- Homework list: 4-color status badges with proper filtering
- API routes: /api/curator/upload and /api/curator/audio-upload

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

src/app/curator/homework/[submissionId]/delete-button.tsx

@@ -0,0 +1,40 @@
+"use client";
+
+import { useTransition } from "react";
+import { useRouter } from "next/navigation";
+import { deleteSubmission } from "./actions";
+
+export function DeleteSubmissionButton({
+  submissionId,
+  userName,
+}: {
+  submissionId: string;
+  userName: string;
+}) {
+  const [pending, startTransition] = useTransition();
+  const router = useRouter();
+
+  function handleDelete() {
+    if (!confirm(`Удалить работу студента ${userName}? Это действие нельзя отменить.`)) return;
+    startTransition(async () => {
+      await deleteSubmission(submissionId);
+      router.push("/curator/homework");
+    });
+  }
+
+  return (
+    <button
+      type="button"
+      onClick={handleDelete}
+      disabled={pending}
+      className="text-xs px-3 py-1.5"
+      style={{
+        border: "1px solid var(--border)",
+        color: "oklch(0.577 0.245 27.325)",
+        opacity: pending ? 0.5 : 1,
+      }}
+    >
+      🗑 Удалить работу
+    </button>
+  );
+}