- upgrade JavaScript obfuscator UI with modern Bootstrap 5

- add dark/light theme toggle with persistent preferences
- implement real-time code preview with CodeMirror editor
- add code statistics showing size reduction percentage
- integrate auto-update option with debounce for performance
- add preset configurations (minimal, balanced, aggressive)
- implement custom preset saving/loading via localStorage
- add file import/export functionality
- improve obfuscation options with better tooltips and organization
- add responsive layout for better mobile experience

Author: TobiasMue91