Add course tree, lesson actions, and module description schema

- CourseTree: expandable module/lesson overview with Eye/Video icons
- SortableLessons: Kinescope ID in create form, published toggle, move-to-module dropdown
- Actions: toggleLessonPublished, moveLessonToModule, updateModule with description
- Schema: add description field to Module model + migration

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

src/app/admin/courses/[courseId]/modules/[moduleId]/actions.ts

@@ -14,8 +14,11 @@ async function requireAdmin() {
 export async function createLesson(moduleId: string, courseId: string, formData: FormData) {
   await requireAdmin();
   const title = formData.get("title") as string;
+  const kinescopeId = (formData.get("kinescopeId") as string | null)?.trim() || null;
   const count = await prisma.lesson.count({ where: { moduleId } });
-  const lesson = await prisma.lesson.create({ data: { moduleId, title, order: count } });
+  const lesson = await prisma.lesson.create({
+    data: { moduleId, title, kinescopeId, order: count },
+  });
   revalidatePath(`/admin/courses/${courseId}/modules/${moduleId}`);
   redirect(`/admin/courses/${courseId}/modules/${moduleId}/lessons/${lesson.id}`);
 }
@@ -42,3 +45,46 @@ export async function reorderLessons(moduleId: string, courseId: string, ordered
   );
   revalidatePath(`/admin/courses/${courseId}/modules/${moduleId}`);
 }
+
+export async function toggleLessonPublished(
+  lessonId: string,
+  courseId: string,
+  moduleId: string,
+  currentValue: boolean
+) {
+  await requireAdmin();
+  await prisma.lesson.update({
+    where: { id: lessonId },
+    data: { published: !currentValue },
+  });
+  revalidatePath(`/admin/courses/${courseId}/modules/${moduleId}`);
+  revalidatePath(`/admin/courses/${courseId}`);
+}
+
+export async function moveLessonToModule(
+  lessonId: string,
+  targetModuleId: string,
+  courseId: string,
+  sourceModuleId: string
+) {
+  await requireAdmin();
+  // verify target module belongs to same course
+  const target = await prisma.module.findFirst({
+    where: { id: targetModuleId, courseId },
+  });
+  if (!target) throw new Error("Module not found");
+
+  const maxOrder = await prisma.lesson.aggregate({
+    where: { moduleId: targetModuleId },
+    _max: { order: true },
+  });
+
+  await prisma.lesson.update({
+    where: { id: lessonId },
+    data: { moduleId: targetModuleId, order: (maxOrder._max.order ?? -1) + 1 },
+  });
+
+  revalidatePath(`/admin/courses/${courseId}/modules/${sourceModuleId}`);
+  revalidatePath(`/admin/courses/${courseId}/modules/${targetModuleId}`);
+  revalidatePath(`/admin/courses/${courseId}`);
+}