- 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)
- markdown: new directives `:::figure assets/x.png | Подпись` and
`:::video assets/x.mp4 | Подпись` rendered as figure/figcaption and a
video player (works with HTML escaping on); sanitizer allows video/source/
track/figure with safe attributes only
- assets: video extensions (mp4/webm/ogg) allowed, separate limits — images
up to 10 MB, video up to 100 MB; correct content types
- upload limits raised: web/academic multipart 120 MB per file / 200 MB per
request, nginx client_max_body_size 200m (covers media inside ZIP imports)
- docs: new docs/06-authoring.md (markdown, images, video, assets, limits,
import semantics); import message now says "медиафайлов"
