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.

inc/modules/user-parts/template-registry.php

@@ -113,12 +113,6 @@ $_aksrt_special_templates = [
         'title'    => '我的订单',
         'fallback' => '/orders/',
     ],
-    'cart' => [
-        'file'     => 'templates/pages/page-cart.php',
-        'slug'     => 'cart',
-        'title'    => '购物车',
-        'fallback' => '/cart/',
-    ],
     'revenue' => [
         'file'     => 'templates/pages/page-revenue.php',
         'slug'     => 'revenue',
@@ -413,11 +407,6 @@ function aksrt_get_current_special_template_path(): string {
         return $orders_template ?: '';
     }
 
-    if (get_query_var('aksrt_cart')) {
-        $cart_template = aksrt_locate_template_file('templates/pages/page-cart.php');
-        return $cart_template ?: '';
-    }
-
     if (get_query_var('aksrt_revenue')) {
         $revenue_template = aksrt_locate_template_file('templates/pages/page-revenue.php');
         return $revenue_template ?: '';

inc/modules/widgets-register.php

@@ -92,12 +92,7 @@ function aksrt_register_widgets() {
 		register_widget('\AKSRT\Widgets\WidgetIconCoverCards');
 		register_widget('\AKSRT\Widgets\WidgetBookmarkLinks');
 
-	// Shop product widgets (§6.9)
-	register_widget('\AKSRT\Widgets\WidgetProductList');
-	register_widget('\AKSRT\Widgets\WidgetProductOneline');
-	register_widget('\AKSRT\Widgets\WidgetProductTab');
-
-	aksrt_maybe_repair_sidebar_blog_widgets();
+		aksrt_maybe_repair_sidebar_blog_widgets();
 }
 add_action('widgets_init', 'aksrt_register_widgets');