Title: Add Email and Phone Columns to the PrestaShop Order List

My store is running PrestaShop 1.6.1.6 and I need a small yet precise back-office tweak. In the Orders list I want two extra columns—customer email and customer account phone number—shown right beside the existing Order ID, customer name, total, etc. The data is already stored; it simply isn’t visible.

What I expect
• Full email address and full phone number displayed for every order.
• The phone value must be pulled from the customer’s account record, not the billing or delivery address.
• Staff must be able to search and sort the grid by these two new columns exactly as they do with the other fields.
• The solution has to be upgrade-friendly: an override of AdminOrdersController, a template override, or a small module rather than a core edit so future patches won’t wipe the change.

When you reply, please outline:
– The approach you would use (e.g., controller override, module, hook, Smarty template).
– Any previous experience you have specifically with PrestaShop 1.6.x customisations.
– An estimated cost and timeline to deliver and test the change.

Clean, maintainable code and a brief note of what you modified will be the final deliverable.