Phase 7: deployment, data import, UI hardening and security fixes

Docker/prod deployment:
- multi-stage Dockerfile (JDK21 build, JRE21 run), docker-compose.prod.yml,
  nginx config for lms.our-place.ru, deploy.sh; DEPLOY/IMPORT guides (UI flow)
- Fix Docker 401: LMS_JWT_JWK_SET_URI for academic/progress; forward-headers

Variant distribution (lab page only):
- round-robin by student level, shared random queue across selected groups,
  least-used variants, manual pins always preserved; occupied/dup labels
- setup page: single form + one «Сохранить всё», batch level/variant for
  selected students (checkboxes)

Grades, defense, materials:
- publication gate + comment lists; defense CSV import (2/3 cols, quotes)
- additional task after defense ("начать заново"); enroll/unenroll students
  from group page; temporary-password lock (no navigation until changed) and
  persistent "Смена пароля"; forced change once
- chapter page /learn/{c}; header: LMS home, Войти, user -> dashboard,
  compact theme toggle; responsive mobile header
- markdown: single newlines are soft breaks; highlight.js with light/dark themes
- lab/content imports ZIP-only (lab.yaml+README+variants/assets,
  chapters tree+assets); duplicate lab numbers rejected; variant ordering
  and date defaults honored

Fixes:
- 500 on student create (@MapsId set before persist); broken dialogs/JS refs in group page

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

@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<html lang="ru" xmlns:th="http://www.thymeleaf.org" th:replace="~{fragments/base :: layout(~{::title}, ~{::#content})}">
+<head><title th:text="${chapter.title} + ' — LMS'">Глава</title></head>
+<body>
+<div id="content">
+    <nav class="text-sm mb-4 breadcrumb">
+        <a th:href="@{/learn}" class="nav-link">Материалы</a>
+        <span class="nav-sep">/</span>
+        <span th:text="${chapter.title}">Глава</span>
+    </nav>
+    <h1 class="page-title" th:text="${chapter.title}">Глава</h1>
+
+    <div th:if="${#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>
+        </h2>
+        <ul class="list-pad text-sm">
+            <li th:each="article : ${section.articles}">
+                <a th:href="@{/learn/{c}/{s}/{a}(c=${chapter.slug}, s=${section.slug}, a=${article.slug})}"
+                   th:text="${article.title}">Статья</a>
+            </li>
+            <li th:if="${#lists.isEmpty(section.articles)}" class="text-muted">Статей пока нет</li>
+        </ul>
+    </div>
+</div>
+</body>
+</html>