Language picker:
- Add fallback href in Pug so language links navigate even if JS fails
- Anchor dropdown to right edge (right:0) so it stays on-screen when
the picker is near the right side of the footer on mobile
Editor layout:
- Read stored pdfLayout from localStorage on init so the last-used
layout is remembered across sessions
- Default to verticalSplit (top/bottom) on mobile when no preference
is stored, so the editor opens in a sensible layout on phones
Translations:
- Add top_bottom_split_view key to all 16 locales that were missing it
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
