Create a database schema for a restaurant management system. The system needs to handle:

- Menu items with categories, prices, and availability
- Table reservations with time slots and party sizes
- Customer orders (dine-in, takeaway, delivery) with order items and status tracking
- Staff management with roles (chef, waiter, manager, delivery) and shift scheduling
- Inventory tracking for ingredients with supplier information and reorder levels
- Billing and payments with support for split bills and multiple payment methods
- Customer loyalty program with points and rewards