mathieu
589aab7e3d
Introduces a global design system using CSS custom properties as design tokens. Light and dark themes are defined via [data-theme] attribute on <html>; the system preference (prefers-color-scheme) is the default when no explicit choice is stored. ThemeToggle component (Auto → Light → Dark cycle) persists the choice to localStorage and applies it on hydration without flash. New themes can be added by defining a [data-theme="name"] CSS block and adding a variant to ThemeChoice. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>