feat: Enhanced Exercise Creation System with Manual/AI Mode Selection

- Add ExerciceModalSelector component for choosing exercise creation mode (Manual/AI)
- Update ExerciceDetailDrawer to handle new exercise types and manual mode display
- Enhance ExerciceForm with additional fields and improved validation
- Extend exercise type definitions to support manual exercise data structure
- Implement ExerciceManualForm with comprehensive question builder functionality
  - Support for multiple question types (multiple choice, true/false, short answer, essay, fill-in-blank)
  - Question reordering with drag-and-drop functionality
  - Document attachment system with upload progress
  - Advanced exercise settings (time limits, scoring, shuffling)
- Integrate ConditionalComponent for cleaner conditional rendering value
- Add proper TypeScript type safety with question type guards
- Implement QuestionBuilder modal for creating and editing individual questions