- add fitMode selector with stretch, crop, and letterbox options

- implement WebP support detection with fallback to PNG
- add safety limits: 10MB file size and 4000px dimension maximum
- fix incorrect rotation and aspect ratio calculations
- improve memory management with canvas cleanup
- add timeouts for image loading (20s) and processing (30s)
- enhance error handling with specific user-friendly messages
- fix swapped horizontal/vertical flip icons
- add processing state management to prevent concurrent operations
- implement unload warning when processing is in progress
- add validation for image URL and dimension inputs

Author: TobiasMue91