feat: Complete mobile UX/UI overhaul

Major improvements:
- New CSS design system with custom properties (tokens)
- Consistent spacing scale (4px base)
- Touch-friendly sizing (44px min targets)
- Improved Carousel with better touch handling and rubber-band effect
- Enhanced FilterControls (auto-collapse on mobile)
- Better stat card styling with change indicators
- Refined chart cards and toggle switches
- Smoother transitions and micro-interactions
- Better RTL support
- Print styles
- Responsive breakpoints for tablet (1024px), mobile (768px), and small mobile (375px)
- Cleaner typography hierarchy
- Subtle shadows and depth

Components updated:
- App.css: Complete rewrite with design tokens
- Carousel.jsx: Better touch gestures with velocity detection
- StatCard.jsx: Improved change indicator styling
- FilterControls.jsx: Auto-collapse on mobile
- EmptyState.jsx: Better accessibility
- ChartExport.js: Cleaned up unused imports

public/index.html

@@ -17,7 +17,7 @@
     <link rel="manifest" href="%PUBLIC_URL%/manifest.json" />
     <link rel="preconnect" href="https://fonts.googleapis.com">
     <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
-    <link href="https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;600&display=swap" rel="stylesheet">
+    <link href="https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;600&family=Tajawal:wght@400;500;700&display=swap" rel="stylesheet">
     <!--
       Notice the use of %PUBLIC_URL% in the tags above.
       It will be replaced with the URL of the `public` folder during the build.