Release version 1.1.20 - Fix WooCommerce Blocks fatal error

## Fixed
- Fatal error in WooCommerce Blocks: "Cannot use object of type WC_Product_Simple as array"
- Error occurred in class-wc-tpp-cart.php:233 in block_quantity_editable() method

## Technical Details
- Filter woocommerce_store_api_product_quantity_editable passes WC_Product object as second parameter, not cart item array
- Updated method signature from block_quantity_editable($editable, $cart_item) to block_quantity_editable($editable, $product)
- Changed parameter access from $cart_item['id'] to $product->get_id()
- Added proper product object validation with is_a($product, 'WC_Product')

## Added
- CLAUDE.md - Comprehensive AI context document for future development
- Complete project architecture documentation
- Historical bug context and solutions
- Development guidelines and testing checklists

## Release
- Version bumped to 1.1.20
- Release package created with MD5 and SHA256 checksums

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

wc-tier-and-package-prices.php

@@ -4,7 +4,7 @@
  * Plugin Name: WooCommerce Tier and Package Prices
  * Plugin URI: https://src.bundespruefstelle.ch/magdev/wc-tier-package-prices
  * Description: Add tier pricing and package prices to WooCommerce products with configurable quantities at fixed prices
- * Version: 1.1.19
+ * Version: 1.1.20
  * Author: Marco Graetsch
  * Author URI: https://src.bundespruefstelle.ch/magdev
  * Text Domain: wc-tier-package-prices
@@ -23,7 +23,7 @@ if (!defined('ABSPATH')) {
 
 // Define plugin constants
 if (!defined('WC_TPP_VERSION')) {
-    define('WC_TPP_VERSION', '1.1.19');
+    define('WC_TPP_VERSION', '1.1.20');
 }
 if (!defined('WC_TPP_PLUGIN_DIR')) {
     define('WC_TPP_PLUGIN_DIR', plugin_dir_path(__FILE__));