feat(a11y,ux): implement comprehensive accessibility and UX optimizations

Phase 1: Accessibility Optimizations
- Add proper label associations and ARIA attributes to form inputs
- Implement aria-required, aria-invalid, aria-describedby for better form accessibility
- Add role='alert' for error messages
- Enhance keyboard navigation with aria-expanded, aria-controls
- Add aria-label for mobile menu button
- Implement aria-current for active navigation items
- Add semantic HTML with aria-labelledby for sections

Phase 2: UX Optimizations
- Create loading skeleton components for better loading states
- Add FormSkeleton, SectionSkeleton, and LoadingSkeleton components
- Prepare for lazy loading implementation

Files modified:
- src/components/ui/input.tsx: Enhanced with ARIA attributes
- src/components/ui/textarea.tsx: Enhanced with ARIA attributes
- src/components/layout/header.tsx: Added navigation ARIA labels
- src/components/sections/hero-section.tsx: Added section labels
- src/components/sections/services-section.tsx: Added section labels
- src/components/ui/loading-skeleton.tsx: New loading state components

Impact:
- WCAG 2.1 AA compliance improvements
- Better screen reader support
- Enhanced keyboard navigation
- Improved user feedback during loading

package.json

@@ -12,6 +12,7 @@
     "@antv/g2": "^5.4.8",
     "@radix-ui/react-dialog": "^1.1.15",
     "@radix-ui/react-dropdown-menu": "^2.1.16",
+    "@types/three": "^0.183.1",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "framer-motion": "^12.34.3",
@@ -20,6 +21,7 @@
     "react": "19.2.3",
     "react-dom": "19.2.3",
     "tailwind-merge": "^3.4.0",
+    "three": "^0.183.1",
     "zod": "^4.3.6"
   },
   "devDependencies": {