Fix licensed variable products showing as sold out (v0.5.11)

- Fixed is_purchasable() method in LicensedVariableProduct to delegate to
  parent WC_Product_Variable instead of checking for price (variable products
  don't have direct prices, only their variations do)
- Fixed getProductClass() filter to accept all 4 WooCommerce parameters
  and use product_id for reliable variation parent detection
- Fallback to global $post when product_id not available for backwards compat

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

CHANGELOG.md

@@ -7,6 +7,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.5.11] - 2026-01-27
+
+### Fixed
+
+- **CRITICAL:** Fixed "sold out" message on licensed variable products by correcting `is_purchasable()` method
+- Variable products don't have a direct price - `is_purchasable()` now delegates to parent `WC_Product_Variable` class
+- Fixed variation class detection by using product ID parameter instead of unreliable global `$post`
+- Product class filter now properly accepts all 4 WooCommerce filter parameters for reliable variation detection
+
 ## [0.5.10] - 2026-01-27
 
 ### Fixed