feat: remove shop feature (Phase 2)

Delete all shop domain classes, controllers, schema builders, templates,
JS/CSS, admin SPA pages, and shop-only payment classes (Shipping,
AfterSale, Discount). Remove shop-only DB table definitions (product_variant,
after_sale, order_shipping, card_key) from migrator and add their DROP
to uninstall.php. Clean up shared files:

- Remove aksrt_product CPT + taxonomies from Setup.php
- Remove shop rewrite rules/query vars/template redirect from SetupPart2.php
- Remove shop widget areas from SetupPart1.php
- Remove shop enqueues from ScriptsPart1b.php
- Remove sepakerator-aksrt-shop from SetupPart2.php
- Remove get_shop_settings facade (delete ForumShop.php, clean DomainGroups.php)
- Remove ORDER_PRODUCT_SHOP constant from DomainModel.php
- Remove Shop::class fallback branches from UserOrders.php, OrderCenterRest.php
- Remove shipping/after-sale branches from OrderRepositoryAdmin.php, PayMenus.php, PayOrders.php
- Remove shop product widgets from widgets-register.php
- Remove cart page from template-registry.php, routing.php, ScriptsPart2.php
- Remove cart UI from sidebar-nav.php, profile-orders.php, sidebar-orders.php
- Clean up order-center.js (remove rebuy/cartUrl/receipt/after-sale handlers)
- Remove aksrt_get_cart_page_url/product_page/product_edit from transactions.php
- Clean up aksrt_product_cat references in Coupon.php, PayCoupons.php

Shared payment/order/credits/content-pay stack fully retained.

src/AKSRT/Payment/Coupon.php

@@ -159,7 +159,7 @@ class Coupon {
         }
 
         // Product / content scope check.
-        // Supports shop product cats and content post cats.
+        // Supports product and content post cats.
         if (!empty($coupon['product_scope']) && !empty($args['product_ids'])) {
             $scope = is_array($coupon['product_scope']) ? $coupon['product_scope'] : json_decode($coupon['product_scope'], true);
             if (is_array($scope) && !empty($scope)) {
@@ -168,11 +168,7 @@ class Coupon {
                 $product_ids = array_map('intval', (array) $args['product_ids']);
                 $taxonomies = array_values(array_filter(array_map('sanitize_key', (array) ($scope['taxonomies'] ?? []))));
                 if ($taxonomies === []) {
-                    // content context prefers category; shop admin may pass aksrt_product_cat.
-                    $context = sanitize_key((string) ($args['context'] ?? ''));
-                    $taxonomies = ($context === 'content')
-                        ? ['category']
-                        : ['aksrt_product_cat', 'category'];
+                    $taxonomies = ['aksrt_product_cat', 'category'];
                 }
 
                 if ($scope_type === 'include' && empty(array_intersect($product_ids, $scope_ids))) {