Website Sale Order Shipping Modification

This module adds an "Edit shipping address" link on the portal page of a quotation. The link appears only when the quotation is in the "sent" state, is not expired, and the delivery address is the same as the invoice address; if the addresses differ, a shorter "Edit" link appears next to the shipping address instead.

Clicking the link opens the standard website checkout address page, but in a special mode: the usual checkout wizard, order summary, and billing address row are hidden, and the website header and footer are removed so the user focuses on the address form. The user can pick or create a delivery address using the familiar address selector.

When the user confirms, the system keeps the original quotation's customer, payment terms, and pricelist. If the fiscal position changed because of the new address, taxes are recalculated; if the pricelist changed, prices are recomputed. The user is then redirected back to the portal order page.

The module touches the website checkout flow and the portal order page. It works with sale.order and res.partner data behind the scenes, and it relies on session flags to know that the user is editing an existing quotation rather than shopping normally.