[Issue]: Database schema: receipts with price #16

Branch Name

feature/16-receipts-price

Task

Description
Design the tables for receipts, including the price information needed for invoice calculations. For DB schemas we use https://dbdiagram.io/

Scope

• receipts table with price
• Link between receipts, donors and food items
• Migration

Acceptance Criteria

• A receipt is linked to its donor and its food items
• Prices are stored in a way that supports invoice calculations
• The migration applies cleanly on an empty database

Checklist

• I have checked for duplicate issues.
• I have assigned the issue to the correct project board.
• I have tagged the issue properly.

Code of Conduct

• I agree to follow this project's Code of Conduct