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/application.yml

@@ -1,10 +1,14 @@
 server:
   port: ${SERVER_PORT:8090}
+  # За nginx: доверяем X-Forwarded-Proto/Host, чтобы редиректы были https и с верным хостом.
+  forward-headers-strategy: framework
   servlet:
     session:
+      timeout: 30d
       cookie:
         http-only: true
         same-site: lax
+        max-age: 30d
       tracking-modes: cookie
 
 spring: