- completely redesign UI with modern Bootstrap 5 layout

- add interactive before/after image comparison slider
- implement dark mode toggle with localStorage persistence
- add zoom controls for image inspection
- expand filter algorithms (add denoise and sharpen options)
- improve export functionality with format and quality options
- add detailed image information display
- implement loading overlay during processing
- add tooltips explaining filter algorithms
- replace static sidebar.js with logo.js reference

Author: TobiasMue91