Add lesson complete button with homework-aware logic

- Show "Отметить как пройденный" button only on lessons without homework
- Show static "Пройдено" badge on homework lessons completed via approval
- Auto-create LessonProgress when curator/admin approves homework submission
- Revalidate student lesson, course, and dashboard pages on approval

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

src/components/student/lesson-complete-button.tsx

@@ -8,13 +8,24 @@ export function LessonCompleteButton({
   lessonId,
   slug,
   isCompleted,
+  readOnly = false,
 }: {
   lessonId: string;
   slug: string;
   isCompleted: boolean;
+  readOnly?: boolean;
 }) {
   const [pending, startTransition] = useTransition();
 
+  if (readOnly) {
+    return (
+      <div className="btn-aubade btn-aubade-accent flex items-center gap-2 px-5 py-2.5 text-sm cursor-default select-none">
+        <Check size={15} strokeWidth={3} />
+        Пройдено
+      </div>
+    );
+  }
+
   return (
     <button
       onClick={() => startTransition(() => toggleLessonProgress(lessonId, slug))}