Add mobile accessibility and UI/UX improvements

- Add mobile card view for packages (replaces table on small screens)
- Implement design tokens system for consistent styling
- Add dark/light theme toggle with system preference support
- Create reusable StatusBadge and EmptyState components
- Add accessible form labels to package filters
- Add compact mobile stats display in navigation
- Add safe area insets for notched devices
- Add reduced motion support for accessibility
- Improve touch targets for WCAG compliance
- Add unit tests for composables
- Update Vuetify configuration and styling

frontend/src/assets/styles/base.scss

@@ -1,2 +1,3 @@
 @use "@fontsource/roboto";
 @use "fork-awesome/css/fork-awesome.min.css";
+@use "./tokens.scss";