- redesign UI with responsive card-based layout

- add color distribution analysis with percentage display
- implement drag-and-drop file upload functionality
- add approximate color naming feature
- create export options (CSS, SCSS, JSON, text formats)
- add sort by brightness functionality
- improve color format display (HEX, RGB, HSL)
- implement toast notification system
- add dark mode support via CSS variables
- optimize mobile responsiveness

Author: TobiasMue91