fix: Newsletter React error #310 and refactor Wishlist module

Newsletter Fix:
- Move all hooks (useQuery, useMutation) before conditional returns
- Add 'enabled' option to useQuery to control when it fetches
- Fixes React error #310: useEffect called conditionally
- Newsletter page now loads without errors at /marketing/newsletter

Wishlist Module Refactoring:
- Create WishlistSettings.php with 8 configurable settings:
  * Enable guest wishlists
  * Wishlist page selector
  * Show in header toggle
  * Enable sharing
  * Back in stock notifications
  * Max items per wishlist
  * Multiple wishlists support
  * Show add to cart button
- Add has_settings flag to wishlist module in ModuleRegistry
- Initialize WishlistSettings in woonoow.php
- Update customer-spa BaseLayout to use isEnabled('wishlist') check
- Wishlist page already has module check (no changes needed)

Files Added (1):
- includes/Modules/WishlistSettings.php

Files Modified (5):
- admin-spa/src/routes/Marketing/Newsletter.tsx
- includes/Core/ModuleRegistry.php
- woonoow.php
- customer-spa/src/layouts/BaseLayout.tsx
- admin-spa/dist/app.js (rebuilt)

Both newsletter and wishlist now follow the same module pattern:
- Settings via schema (no code required)
- Module enable/disable controls feature visibility
- Settings page at /settings/modules/{module_id}
- Consistent user experience

includes/Modules/WishlistSettings.php

@@ -0,0 +1,95 @@
+<?php
+/**
+ * Wishlist Module Settings
+ *
+ * @package WooNooW
+ */
+
+namespace WooNooW\Modules;
+
+if (!defined('ABSPATH')) exit;
+
+class WishlistSettings {
+    
+    /**
+     * Initialize the settings
+     */
+    public static function init() {
+        add_filter('woonoow/module_settings_schema', [__CLASS__, 'register_schema']);
+    }
+    
+    /**
+     * Register wishlist settings schema
+     */
+    public static function register_schema($schemas) {
+        $schemas['wishlist'] = [
+            'enable_guest_wishlist' => [
+                'type' => 'toggle',
+                'label' => __('Enable Guest Wishlists', 'woonoow'),
+                'description' => __('Allow non-logged-in users to create wishlists (stored in browser)', 'woonoow'),
+                'default' => true,
+            ],
+            'wishlist_page' => [
+                'type' => 'select',
+                'label' => __('Wishlist Page', 'woonoow'),
+                'description' => __('Page to display wishlist items', 'woonoow'),
+                'placeholder' => __('-- Select Page --', 'woonoow'),
+                'options' => self::get_pages_options(),
+            ],
+            'show_in_header' => [
+                'type' => 'toggle',
+                'label' => __('Show Wishlist Icon in Header', 'woonoow'),
+                'description' => __('Display wishlist icon with item count in the header', 'woonoow'),
+                'default' => true,
+            ],
+            'enable_sharing' => [
+                'type' => 'toggle',
+                'label' => __('Enable Wishlist Sharing', 'woonoow'),
+                'description' => __('Allow users to share their wishlists via link', 'woonoow'),
+                'default' => true,
+            ],
+            'enable_email_notifications' => [
+                'type' => 'toggle',
+                'label' => __('Back in Stock Notifications', 'woonoow'),
+                'description' => __('Email users when wishlist items are back in stock', 'woonoow'),
+                'default' => false,
+            ],
+            'max_items_per_wishlist' => [
+                'type' => 'number',
+                'label' => __('Maximum Items Per Wishlist', 'woonoow'),
+                'description' => __('Limit the number of items in a wishlist (0 = unlimited)', 'woonoow'),
+                'default' => 0,
+                'min' => 0,
+                'max' => 1000,
+            ],
+            'enable_multiple_wishlists' => [
+                'type' => 'toggle',
+                'label' => __('Enable Multiple Wishlists', 'woonoow'),
+                'description' => __('Allow users to create multiple named wishlists', 'woonoow'),
+                'default' => false,
+            ],
+            'show_add_to_cart_button' => [
+                'type' => 'toggle',
+                'label' => __('Show "Add to Cart" on Wishlist Page', 'woonoow'),
+                'description' => __('Display add to cart button for each wishlist item', 'woonoow'),
+                'default' => true,
+            ],
+        ];
+        
+        return $schemas;
+    }
+    
+    /**
+     * Get WordPress pages as select options
+     */
+    private static function get_pages_options() {
+        $pages = get_pages();
+        $options = [];
+        
+        foreach ($pages as $page) {
+            $options[$page->ID] = $page->post_title;
+        }
+        
+        return $options;
+    }
+}