- redesign UI with tabs for basics, characters, structure, advanced, script, and history

- add dark/light theme toggle with persistent preference
- implement basic/advanced mode toggle with conditional field display
- add character management system with customizable roles and descriptions
- introduce script history with local storage persistence
- enhance form with additional fields for tone, pacing, structure templates, and settings
- improve UX with notifications, loading animations, and tooltips
- optimize responsiveness for mobile devices
- add save/load functionality for project settings

Author: TobiasMue91