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

package.json

@@ -10,6 +10,7 @@
     "@testing-library/user-event": "^13.5.0",
     "chart.js": "^4.5.1",
     "chartjs-plugin-datalabels": "^2.2.0",
+    "html2canvas": "^1.4.1",
     "jszip": "^3.10.1",
     "react": "^19.2.4",
     "react-chartjs-2": "^5.3.1",