EDD 'edit discount code' link generates 'Invalid nonce' error #183

Description

The "edit discount code" link on the Sitewide Sale edit page is broken — clicking it results in errors instead of opening the EDD discount editor.

Root Cause

The URL uses edd-action=edit_discount, which triggers EDD's discount save/update handler (requiring nonce validation). The correct parameter for loading the edit screen is view=edit_discount.

Affected code: modules/ecommerce/edd/class-swsales-module-edd.php (line 143) and modules/ecommerce/edd/swsales-module-edd-metaboxes.js (line 14).

Steps to Reproduce

1. Create or edit a Sitewide Sale with the EDD sale type
2. Select an existing EDD discount code
3. Click the "edit discount code" button
4. Result: EDD shows an error or redirect loop

Expected Behavior

The "edit discount code" link should open the EDD discount edit page.

Fix

Replace edd-action=edit_discount with view=edit_discount in both PHP and JS. See PR #184.