If no lesson loads within 3 seconds, show a centered, gray notice
with fade-in animation suggesting to select from menu or check help.
Includes link to help dialog.
- Add contact section to help dialog with librete.ch, GitHub, Gitea, LinkedIn links
- Add HTML/CSS prefixes to English module titles for consistency with German
- Add CSS transitions for smooth lesson switching
- Add transitioning class to prevent content flash during lesson changes
- Wrap lesson label in span for mobile hiding
- Truncate module name with ellipsis if too long
- Hide "Lesson/Lektion" label on mobile, show only "1 / 3"
- Add lessonLabel i18n keys for EN/DE
- Create i18n.js module with EN/DE translations
- Add data-i18n attributes to index.html for dynamic text
- Update renderer.js to use translation functions
- Language switcher button replaces link to German page
- Stores preference in localStorage, detects browser language