- Add Detail endpoint to LessonsController (GET /Plugins/Lessons/Detail?id=...)
- Update lessonsPage.html with detail view, click handlers, and back navigation
- Media cards fetch Jellyfin item details and render thumbnails & durations
- Clicking media card launches Jellyfin native player via appRouter.showItem
- Compiled Typst HTML rendered via innerHTML with dark theme styling
- Works on web and Fire TV Silk browser
Closes#6