Learn: remember expanded sections, open only in the last chapter by default

web/src/main/resources/templates/learn/chapter.html

@@ -47,12 +47,13 @@
     </div>
 
     <div class="card card-body chapter-card mb-4" data-section-list>
-        <div th:each="section : ${chapter.sections}" class="sub-acc" th:attr="data-section-id=${section.id}">
+        <div th:each="section : ${chapter.sections}" class="sub-acc collapsed"
+             th:attr="data-section-id=${section.id}">
             <div class="sub-head sort-row">
                 <span th:if="${currentUser != null and currentUser.admin}" class="drag-handle" draggable="true"
                       th:attr="data-drag-kind='section',data-drag-id=${section.id}"
                       title="Перетащите мышью: изменить порядок разделов">⠿</span>
-                <button type="button" class="sub-toggle" aria-expanded="true" onclick="toggleSection(this)"
+                <button type="button" class="sub-toggle" aria-expanded="false" onclick="toggleSection(this)"
                         title="Свернуть или развернуть раздел">
                     <span class="sub-arrow" aria-hidden="true"></span>
                 </button>