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

Closes IA-692