Voucher gets removed when navigating back to cart and returning to checkout

Describe the bug
In the Enatega Multivendor app, after applying a voucher in the Checkout section, if the user navigates back to the Cart screen and then returns to the Checkout screen, the applied voucher disappears automatically.

To Reproduce
Steps to reproduce the behavior:

Open the Enatega Multivendor app.
Add items to cart and proceed to Checkout.
Apply a voucher code successfully.
Navigate back to the Cart screen.
Go back again to the Checkout screen.
Expected behavior
The applied voucher should remain intact until manually removed by the user.

Screenshots

Desktop (please complete the following information):

OS: [e.g. iOS]
Browser [e.g. chrome, safari]
Version [e.g. 22]
Smartphone (please complete the following information):

Device: [e.g. iPhone6]
OS: [e.g. iOS8.1]
Browser [e.g. stock browser, safari]
Version [e.g. 22]
Additional context
Add any other context about the problem here.

Labels: Enatega Multivendor Customer App, Bug

Start by reproducing the flow through the Checkout and Cart screens after applying a voucher. Trace how the applied voucher is stored when navigating away and back, then verify that it remains applied until manually removed.

Written by the indexing model from the issue text.