Fix stock indicator on licensed variable products (v0.5.12)

- Fixed stock indicator appearing in cart for licensed variable products
- Override get_children() with direct SQL query to bypass WooCommerce type check
- Override get_variation_attributes() for proper taxonomy attribute loading
- Override get_variation_prices() to prevent null array errors
- Override get_available_variations() with empty availability_html
- Added is_type() override to pass variable type checks
- Added multiple stock-related filters for comprehensive coverage
- Improved isLicensedProductOrVariation() with DB-level parent type check

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/Product/LicensedProductVariation.php

@@ -35,6 +35,61 @@ class LicensedProductVariation extends WC_Product_Variation
         return true;
     }
 
+    /**
+     * Licensed products are always in stock (virtual, no inventory)
+     */
+    public function is_in_stock(): bool
+    {
+        return true;
+    }
+
+    /**
+     * Get availability - empty for licensed products (no stock indicator)
+     */
+    public function get_availability(): array
+    {
+        return [
+            'availability' => '',
+            'class'        => '',
+        ];
+    }
+
+    /**
+     * Don't manage stock for licensed products
+     */
+    public function managing_stock(): bool
+    {
+        return false;
+    }
+
+    /**
+     * Check if variation is purchasable
+     * Override to handle custom parent product type
+     */
+    public function is_purchasable(): bool
+    {
+        // Check if variation exists
+        if (!$this->exists()) {
+            return false;
+        }
+
+        // Check parent product status
+        $parentId = $this->get_parent_id();
+        $parentStatus = get_post_status($parentId);
+
+        if ($parentStatus !== 'publish' && !current_user_can('edit_post', $parentId)) {
+            return false;
+        }
+
+        // Check if variation has a price
+        $price = $this->get_price();
+        if ($price === '' || $price === null) {
+            return false;
+        }
+
+        return apply_filters('woocommerce_variation_is_purchasable', true, $this);
+    }
+
     /**
      * Get max activations for this variation
      * Falls back to parent product, then to default settings