Product Cost Price History Views

This module makes the cost price history records that Odoo already stores for products visible and usable.

• A new menu "Product Cost History" appears under Inventory > Inventory Control. It opens a list of price history lines showing the product, the date and the cost, and the same data can be displayed as a graph of cost over time.
• On a product form (both the product template form and the product variant form) a "Price History" button with a history icon is added in the button box. It shows how many history lines exist for that product and opens the list filtered on that product.
• The list of history lines is directly editable, so users can correct the cost value of a line.
• A search view lets users search by product or date and group the lines by product or by date.

The module extends the existing product.price.history model by adding a stored link to the product template and by making the cost field averageable in grouped views. It also adds a computed counter of history lines on product.product and product.template. No new automatic rules, checks or emails are added; it is a viewing and reporting layer on top of the cost history already recorded by Odoo.