- Add 4 bundled fonts: Montserrat, Noto Sans, Source Sans 3, plus
existing LINE Seed JP (default) and System fallback
- Font selector dropdown in Settings > Appearance, after Language
- Persisted in localStorage, applied on app bootstrap via data-font
attribute on <html> which overrides --font-sans CSS variable
- @font-face declarations for variable font files in static/fonts/
- i18n key "fontFamily" added to all 4 locales