React: Convert class component to functional with TypeScript hooks

- Converted class component → functional component with React hooks
- Used useRef<DataGridRef<Sale, number>> for proper DevExtreme React typing
- Wrapped all event handlers in useCallback for performance optimization
- Added proper DevExtreme React types: DataGridTypes, PivotGridTypes
- Implemented early return pattern for null-safe instance access
- Used Fragment syntax (<>) instead of React.Fragment
- Added drillDownDataSourceRef with useRef for state management
- Created data.ts with Sale interface and typed sales array
- Added ESLint disable comments for promise handling
- Removed orig_ reference files

Author: artem-kurchenko