Learn UI: prev/next navigation, sidebar outline, editing on every page; merge import; defense date

- article page: ← / → navigation across the whole material tree (including
  between sections), sticky sidebar outline with the current article highlighted
- editing on chapter, section and article pages: rename, publish/hide, delete,
  create section/article, move articles while deleting a section; forms return
  to the page they were opened from (validated internal `back` parameter)
- article page opens the edit dialog directly via ?edit=1 (used by "Править"
  links on section/chapter pages)
- import: optional sync flag — with it stale sections/articles of archived
  chapters are deleted (previous behaviour), without it import only adds and
  updates, so material edited in the UI is not overwritten
- student area: lab page and lab cards now show the defense date next to the
  submission deadline
- fix SpEL crash on the student lab page (`and` with nullable strings)

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

@@ -8,29 +8,160 @@
         <span class="nav-sep">/</span>
         <span th:text="${chapter.title}">Глава</span>
     </nav>
+
     <h1 class="page-title">
         <span th:text="${chapter.title}">Глава</span>
         <span th:if="${!chapter.published}" class="badge badge-warn ml-2">скрыто</span>
     </h1>
 
+    <div th:if="${currentUser != null and currentUser.admin}" class="flex flex-wrap gap-2 mb-4">
+        <button class="btn btn-primary btn-sm" type="button" onclick="openModal('modal-new-section')">+ Раздел</button>
+        <button class="btn btn-secondary btn-sm" type="button" onclick="openModal('modal-rename-chapter')">Переименовать главу</button>
+        <form class="inline-form" th:action="@{/admin/content/chapters/toggle-published}" method="post">
+            <input type="hidden" name="_csrf" th:value="${csrfToken}">
+            <input type="hidden" name="id" th:value="${chapter.id}">
+            <input type="hidden" name="published" th:value="${!chapter.published}">
+            <input type="hidden" name="back" th:value="${back}">
+            <button class="btn btn-sm" type="submit"
+                    th:classappend="${chapter.published} ? 'btn-secondary' : 'btn-primary'"
+                    th:text="${chapter.published} ? 'Скрыть главу' : 'Опубликовать главу'">Скрыть</button>
+        </form>
+        <form class="inline-form" th:action="@{/admin/content/chapters/{id}/delete(id=${chapter.id})}" method="post"
+              onsubmit="return confirm('Удалить главу со всеми разделами и статьями?')">
+            <input type="hidden" name="_csrf" th:value="${csrfToken}">
+            <input type="hidden" name="back" th:value="${backParent}">
+            <button class="btn btn-danger btn-sm" type="submit">Удалить главу</button>
+        </form>
+    </div>
+
     <div th:if="${#lists.isEmpty(chapter.sections)}" class="card card-body text-muted">
         В этой главе пока нет разделов.
     </div>
 
     <div th:each="section : ${chapter.sections}" class="card card-body mb-4">
-        <h2 class="group-title">
-            <a th:href="@{/learn/{c}/{s}(c=${chapter.slug}, s=${section.slug})}" th:text="${section.title}">Раздел</a>
-            <span th:if="${!section.published}" class="badge badge-warn">скрыто</span>
-        </h2>
+        <div class="flex flex-wrap items-center justify-between gap-2 mb-2">
+            <h2 class="group-title m-0">
+                <a th:href="@{/learn/{c}/{s}(c=${chapter.slug}, s=${section.slug})}" th:text="${section.title}">Раздел</a>
+                <span th:if="${!section.published}" class="badge badge-warn">скрыто</span>
+            </h2>
+            <div th:if="${currentUser != null and currentUser.admin}" class="flex flex-wrap gap-2">
+                <button class="btn btn-secondary btn-sm" type="button"
+                        th:data-modal="|modal-rename-section-${section.id}|" onclick="openModalData(this)">Переименовать</button>
+                <form class="inline-form" th:action="@{/admin/content/sections/toggle-published}" method="post">
+                    <input type="hidden" name="_csrf" th:value="${csrfToken}">
+                    <input type="hidden" name="id" th:value="${section.id}">
+                    <input type="hidden" name="published" th:value="${!section.published}">
+                    <input type="hidden" name="back" th:value="${back}">
+                    <button class="btn btn-sm" type="submit"
+                            th:classappend="${section.published} ? 'btn-secondary' : 'btn-primary'"
+                            th:text="${section.published} ? 'Скрыть' : 'Опубликовать'">Скрыть</button>
+                </form>
+                <button class="btn btn-secondary btn-sm" type="button"
+                        th:data-modal="|modal-move-${section.id}|" onclick="openModalData(this)">Перенести статьи и удалить</button>
+                <form class="inline-form" th:action="@{/admin/content/sections/{id}/delete(id=${section.id})}" method="post"
+                      onsubmit="return confirm('Удалить раздел вместе со статьями?')">
+                    <input type="hidden" name="_csrf" th:value="${csrfToken}">
+                    <input type="hidden" name="back" th:value="${back}">
+                    <button class="btn btn-danger btn-sm" type="submit">Удалить</button>
+                </form>
+            </div>
+        </div>
+
         <ul class="list-pad text-sm">
-            <li th:each="article : ${section.articles}">
+            <li th:each="article : ${section.articles}" class="flex items-center gap-2">
                 <a th:href="@{/learn/{c}/{s}/{a}(c=${chapter.slug}, s=${section.slug}, a=${article.slug})}"
                    th:text="${article.title}">Статья</a>
-                <span th:if="${!article.published}" class="badge badge-warn ml-1">скрыто</span>
+                <span th:if="${!article.published}" class="badge badge-warn">скрыто</span>
+                <th:block th:if="${currentUser != null and currentUser.admin}">
+                    <a class="btn btn-secondary btn-sm"
+                       th:href="@{/learn/{c}/{s}/{a}(c=${chapter.slug}, s=${section.slug}, a=${article.slug}, edit=1)}">Править</a>
+                    <form class="inline-form" th:action="@{/admin/content/articles/toggle-published}" method="post">
+                        <input type="hidden" name="_csrf" th:value="${csrfToken}">
+                        <input type="hidden" name="id" th:value="${article.id}">
+                        <input type="hidden" name="published" th:value="${!article.published}">
+                        <input type="hidden" name="back" th:value="${back}">
+                        <button class="btn btn-sm" type="submit"
+                                th:classappend="${article.published} ? 'btn-secondary' : 'btn-primary'"
+                                th:text="${article.published} ? 'Скрыть' : 'Опубликовать'">Скрыть</button>
+                    </form>
+                </th:block>
             </li>
             <li th:if="${#lists.isEmpty(section.articles)}" class="text-muted">Статей пока нет</li>
         </ul>
+
+        <th:block th:if="${currentUser != null and currentUser.admin}">
+            <dialog th:id="|modal-rename-section-${section.id}|" class="modal">
+                <div class="modal-header">
+                    <h2 class="modal-title">Переименовать раздел</h2>
+                    <button class="modal-close" type="button"
+                            th:data-modal="|modal-rename-section-${section.id}|" onclick="closeModalData(this)">✕</button>
+                </div>
+                <div class="modal-body">
+                    <form class="form-stack" th:action="@{/admin/content/sections/{id}/rename(id=${section.id})}" method="post">
+                        <input type="hidden" name="_csrf" th:value="${csrfToken}">
+                        <input type="hidden" name="back" th:value="${back}">
+                        <div><label class="label">Название</label>
+                            <input class="input" name="title" th:value="${section.title}" required></div>
+                        <button class="btn btn-primary" type="submit">Сохранить</button>
+                    </form>
+                </div>
+            </dialog>
+            <dialog th:id="|modal-move-${section.id}|" class="modal">
+                <div class="modal-header">
+                    <h2 class="modal-title">Перенести статьи из раздела</h2>
+                    <button class="modal-close" type="button"
+                            th:data-modal="|modal-move-${section.id}|" onclick="closeModalData(this)">✕</button>
+                </div>
+                <div class="modal-body">
+                    <form class="form-stack" th:action="@{/admin/content/sections/{id}/delete(id=${section.id})}" method="post">
+                        <input type="hidden" name="_csrf" th:value="${csrfToken}">
+                        <input type="hidden" name="back" th:value="${back}">
+                        <p class="text-sm text-muted">Выберите раздел-приёмник: статьи перенесутся туда, а текущий раздел удалится.</p>
+                        <div><label class="label">Перенести в раздел</label>
+                            <select class="input" name="moveTo">
+                                <option th:each="pair : ${sectionChoices}"
+                                        th:if="${pair['id'] != section.id}"
+                                        th:value="${pair['id']}" th:text="${pair['label']}">—</option>
+                            </select></div>
+                        <button class="btn btn-primary" type="submit">Перенести и удалить</button>
+                    </form>
+                </div>
+            </dialog>
+        </th:block>
     </div>
+
+    <dialog id="modal-rename-chapter" class="modal">
+        <div class="modal-header">
+            <h2 class="modal-title">Переименовать главу</h2>
+            <button class="modal-close" type="button" onclick="closeModal('modal-rename-chapter')">✕</button>
+        </div>
+        <div class="modal-body">
+            <form class="form-stack" th:action="@{/admin/content/chapters/{id}/rename(id=${chapter.id})}" method="post">
+                <input type="hidden" name="_csrf" th:value="${csrfToken}">
+                <input type="hidden" name="back" th:value="${back}">
+                <div><label class="label" for="chTitle">Название</label>
+                    <input class="input" id="chTitle" name="title" th:value="${chapter.title}" required></div>
+                <button class="btn btn-primary" type="submit">Сохранить</button>
+            </form>
+        </div>
+    </dialog>
+
+    <dialog id="modal-new-section" class="modal">
+        <div class="modal-header">
+            <h2 class="modal-title">Новый раздел в главе</h2>
+            <button class="modal-close" type="button" onclick="closeModal('modal-new-section')">✕</button>
+        </div>
+        <div class="modal-body">
+            <form class="form-stack" th:action="@{/admin/content/sections/create}" method="post">
+                <input type="hidden" name="_csrf" th:value="${csrfToken}">
+                <input type="hidden" name="chapterId" th:value="${chapter.id}">
+                <input type="hidden" name="back" th:value="${back}">
+                <div><label class="label" for="secNewTitle">Название раздела</label>
+                    <input class="input" id="secNewTitle" name="title" required></div>
+                <button class="btn btn-primary" type="submit">Создать</button>
+            </form>
+        </div>
+    </dialog>
 </div>
 </body>
 </html>