Enhance Animation Showcase Styling with Advanced Visual Effects and Interactions

- Refactor animations.css with more sophisticated design and color variables
- Add dynamic radial gradient backgrounds and subtle texture overlays
- Improve category tabs with enhanced hover and active states
- Implement 3D card hover effects and refined shadow styles
- Add flash effect for category changes in animation gallery
- Optimize dark mode color scheme and visual hierarchy
- Enhance code panel and customization panel with modern design elements

Author: TMHSDigital