- Add MenuItem model with hierarchical structure support
- Implement recursive menu browsing with infinite depth support
- Add ExpansionTile for collapsible modifier sections
- Implement radio/checkbox logic based on ItemMaxNumSelectionReq
- Add automatic pre-selection for ItemIsCheckedByDefault items
- Implement validation for ItemRequiresChildSelection and max limits
- Add recursive price calculation across all depth levels
- Support intelligent selection behavior (radio groups, parent/child deselection)
- Add proper error messaging for validation failures
- Connect menu items API endpoint
- Update navigation flow to menu browse after service point selection
