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/index.html

@@ -18,7 +18,7 @@
         Материалы ещё не добавлены.
     </div>
 
-    <details th:each="chapter : ${tree?.chapters}" class="card mb-4 accordion" open>
+    <details th:each="chapter, chStat : ${tree?.chapters}" class="card mb-4 accordion" th:attr="open=${chStat.last}">
         <summary class="card-body acc-head">
             <h2 class="section-title acc-title" th:text="${chapter.title}">Глава</h2>
             <span class="acc-arrow" aria-hidden="true"></span>
@@ -39,7 +39,7 @@
 
             <p th:if="${#lists.isEmpty(chapter.sections)}" class="text-sm text-muted">Разделов пока нет</p>
 
-            <details th:each="section : ${chapter.sections}" class="mt-4 sub-acc" open>
+            <details th:each="section : ${chapter.sections}" class="mt-4 sub-acc">
                 <summary class="sub-head">
                     <h3 class="group-title m-0">
                         <span class="sub-arrow" aria-hidden="true"></span>