- complete redesign of emoji search interface with modern UI

- add dark/light theme toggle with local storage persistence
- implement keyboard navigation with arrow keys and shortcuts
- add emoji categories with filtering functionality
- create recent emojis section with localStorage persistence
- improve search algorithm with relevance-based sorting
- add responsive design for mobile devices
- implement emoji size controls with slider
- add tooltips showing emoji keywords
- add copy-to-clipboard with visual feedback via toast notifications
- replace basic CSS with CSS variables for theming

Author: TobiasMue91