Initial implementation of WooCommerce Composable Products plugin

Implemented custom WooCommerce product type allowing customers to build their own
product bundles by selecting from predefined sets of products.

Features:
- Custom "Composable Product" type with admin interface
- Product selection by category, tag, or SKU
- Configurable selection limits (global and per-product)
- Dual pricing modes: fixed price or sum of selected products
- Modern responsive frontend with Twig templates
- AJAX add-to-cart functionality
- Full internationalization support (.pot file)
- WooCommerce settings integration
- Comprehensive documentation

Technical implementation:
- PHP 8.3+ with PSR-4 autoloading
- Twig 3.0 templating engine via Composer
- Vanilla JavaScript with jQuery for frontend interactions
- WordPress and WooCommerce hooks for seamless integration
- Security: input sanitization, validation, and output escaping
- Translation-ready with text domain 'wc-composable-product'

Documentation:
- README.md: Project overview and features
- INSTALL.md: Installation and usage guide
- IMPLEMENTATION.md: Technical architecture
- CHANGELOG.md: Version history

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

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

wc-composable-product.php

@@ -0,0 +1,79 @@
+<?php
+/**
+ * Plugin Name: WooCommerce Composable Products
+ * Plugin URI: https://github.com/magdev/wc-composable-product
+ * Description: Create composable products where customers select a limited number of items from a configurable set
+ * Version: 1.0.0
+ * Author: Marco Graetsch
+ * Author URI: https://example.com
+ * License: GPL v3 or later
+ * License URI: https://www.gnu.org/licenses/gpl-3.0.html
+ * Text Domain: wc-composable-product
+ * Domain Path: /languages
+ * Requires at least: 6.0
+ * Requires PHP: 8.3
+ * WC requires at least: 8.0
+ * WC tested up to: 10.0
+ */
+
+defined('ABSPATH') || exit;
+
+// Define plugin constants
+define('WC_COMPOSABLE_PRODUCT_VERSION', '1.0.0');
+define('WC_COMPOSABLE_PRODUCT_FILE', __FILE__);
+define('WC_COMPOSABLE_PRODUCT_PATH', plugin_dir_path(__FILE__));
+define('WC_COMPOSABLE_PRODUCT_URL', plugin_dir_url(__FILE__));
+define('WC_COMPOSABLE_PRODUCT_BASENAME', plugin_basename(__FILE__));
+
+// Load Composer autoloader
+if (file_exists(WC_COMPOSABLE_PRODUCT_PATH . 'vendor/autoload.php')) {
+    require_once WC_COMPOSABLE_PRODUCT_PATH . 'vendor/autoload.php';
+}
+
+/**
+ * Check if WooCommerce is active
+ */
+function wc_composable_product_check_woocommerce() {
+    if (!class_exists('WooCommerce')) {
+        add_action('admin_notices', function() {
+            ?>
+            <div class="notice notice-error">
+                <p><?php esc_html_e('WooCommerce Composable Products requires WooCommerce to be installed and active.', 'wc-composable-product'); ?></p>
+            </div>
+            <?php
+        });
+        return false;
+    }
+    return true;
+}
+
+/**
+ * Initialize the plugin
+ */
+function wc_composable_product_init() {
+    if (!wc_composable_product_check_woocommerce()) {
+        return;
+    }
+
+    // Load text domain
+    load_plugin_textdomain('wc-composable-product', false, dirname(WC_COMPOSABLE_PRODUCT_BASENAME) . '/languages');
+
+    // Initialize main plugin class
+    WC_Composable_Product\Plugin::instance();
+}
+add_action('plugins_loaded', 'wc_composable_product_init');
+
+/**
+ * Activation hook
+ */
+function wc_composable_product_activate() {
+    if (!class_exists('WooCommerce')) {
+        deactivate_plugins(WC_COMPOSABLE_PRODUCT_BASENAME);
+        wp_die(
+            esc_html__('This plugin requires WooCommerce to be installed and active.', 'wc-composable-product'),
+            esc_html__('Plugin Activation Error', 'wc-composable-product'),
+            array('back_link' => true)
+        );
+    }
+}
+register_activation_hook(__FILE__, 'wc_composable_product_activate');