Product rating verified

This module extends the standard rating feature so that product reviews can show whether the reviewer really bought the product.

• On every rating record, a new read-only field called purchase_verified is calculated automatically. It becomes true only when the rating is linked to a product (product.product) and the same customer has at least one paid customer invoice line for that product.
• The check looks at invoice lines whose payment status is "paid", matching both the customer and the product. If no such paid line exists, the flag stays false.
• The value is stored, so it can be used in filters, groupings or reports without recalculating every time.
• In the rating form view, the field appears right after the internal note indicator, but it is only visible when the rating concerns a product; for other rating types it is hidden.
• The module touches the rating.rating model and the account.move.line data used for the verification. It does not add menus, buttons, emails or scheduled actions of its own.

In short, it gives businesses a simple way to highlight trustworthy product reviews coming from actual paying customers.