- redesign UI with improved layout and responsive elements

- add dark mode support with theme toggle
- implement loading overlay during text processing
- enhance text processing with natural score feedback
- add example texts modal with pre-defined templates
- improve preset management with delete functionality
- add detailed stats for both input and output text
- optimize toast notifications with different status types
- implement character limit warnings
- add fontawesome icons for better visual feedback
- improve input validation and error handling

Author: TobiasMue91