feat: initial implementation of WooList phpList Integration plugin v1.0.0

- phpList REST API wrapper with subscriber get-or-create + list assignment
- WooCommerce Settings tab (5 sections: connection, orders, signup, newsletter)
- Test Connection button via admin-post action
- Hooks for order completed/cancelled and user_register events
- [woolist_newsletter] shortcode with jQuery AJAX, fixed & auto-generated coupons
- Responsive front-end form styles and JS with loading/success/error states

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

woolist-phplist/woolist-phplist.php

@@ -0,0 +1,57 @@
+<?php
+/**
+ * Plugin Name: WooList — phpList Integration
+ * Plugin URI:  https://github.com/woolist/woolist-phplist
+ * Description: Sync WooCommerce customers and newsletter signups to phpList.
+ * Version:     1.0.0
+ * Author:      WooList
+ * Text Domain: woolist-phplist
+ * Domain Path: /languages
+ * Requires at least: 6.0
+ * Requires PHP: 7.4
+ * Requires Plugins: woocommerce
+ *
+ * @package WooList
+ */
+
+defined( 'ABSPATH' ) || exit;
+
+// Plugin constants.
+define( 'WOOLIST_VERSION', '1.0.0' );
+define( 'WOOLIST_PATH', plugin_dir_path( __FILE__ ) );
+define( 'WOOLIST_URL', plugin_dir_url( __FILE__ ) );
+
+/**
+ * Check that WooCommerce is active; show admin notice if not.
+ */
+function woolist_check_woocommerce() {
+	if ( ! class_exists( 'WooCommerce' ) ) {
+		add_action( 'admin_notices', function () {
+			echo '<div class="notice notice-error"><p>'
+				. esc_html__( 'WooList — phpList Integration requires WooCommerce to be installed and active.', 'woolist-phplist' )
+				. '</p></div>';
+		} );
+		return false;
+	}
+	return true;
+}
+
+/**
+ * Bootstrap the plugin after all plugins are loaded.
+ */
+function woolist_init() {
+	if ( ! woolist_check_woocommerce() ) {
+		return;
+	}
+
+	require_once WOOLIST_PATH . 'includes/class-woolist-api.php';
+	require_once WOOLIST_PATH . 'includes/class-woolist-admin.php';
+	require_once WOOLIST_PATH . 'includes/class-woolist-hooks.php';
+	require_once WOOLIST_PATH . 'includes/class-woolist-shortcode.php';
+
+	$api = new WooList_API();
+	new WooList_Admin( $api );
+	new WooList_Hooks( $api );
+	new WooList_Shortcode( $api );
+}
+add_action( 'plugins_loaded', 'woolist_init' );