- modernize UI with responsive design and improved styling

- implement real-time QR generation with debounce functionality
- add preset content types (text, URL, email, phone, SMS, WiFi)
- enhance logo integration with size controls and circular mask
- optimize mobile experience with viewport meta tag
- replace sidebar.js reference with logo.js
- add input validation for different content types
- implement loading indicator during QR generation

Author: TobiasMue91