feat:hide Last Purchase Rate unless user has Purchase User role

[arathipk]

Feature description

--Hide last purchase rate in sales order & Quotation – show only if user has Purchase User role
--show Customer Name instead of ID

Solution description

 --Hid last purchase rate 
 --showed Customer Name instead of ID

Output screenshots (optional)

Screencast.from.2026-02-05.17-16-19.webm

Is there any existing behavior change of other features due to this code change?

-- No. If Yes, provide the appropriate explanation.

Was this feature tested on the browsers?

--Mozilla Firefox

[sivajyothis7]

last_purchase_rate should be fetched from Item master instead of querying Purchase Invoice Item.