Add WooCommerce-to-Twig rendering bridge

Intercept WooCommerce's PHP template loading via
woocommerce_before_template_part / woocommerce_after_template_part hooks
to render Bootstrap 5 Twig templates instead. This makes all 99 child
theme templates functional in a standard WooCommerce environment.

- Create WooCommerceExtension (Twig AbstractExtension) with ~50 functions
  and 7 filters covering WC API, WordPress hooks, escaping, and forms
- Rewrite TemplateOverride to use hook-based interception with stack-based
  output buffering for nested template support
- Wire bridge initialization at init priority 20 in functions.php
- Fix invalid {% do return() %} in two order templates

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

functions.php

@@ -43,16 +43,42 @@ function wc_bootstrap_setup(): void {
 add_action( 'after_setup_theme', 'wc_bootstrap_setup' );
 
 /**
- * Register plugin template overrides.
+ * Initialize the WooCommerce-to-Twig template bridge.
  *
- * Prepends the child theme's templates/ directory to the plugin's Twig loader,
- * so child theme templates take priority over plugin templates.
+ * Registers the WooCommerce Twig extension with the parent theme's TwigService
+ * and sets up template interception hooks so the child theme's Twig templates
+ * are rendered instead of WooCommerce's PHP templates.
+ *
+ * Runs at 'init' priority 20 to ensure WooCommerce is fully loaded (it
+ * initializes at 'init' priority 0).
  */
-function wc_bootstrap_register_template_override(): void {
+function wc_bootstrap_init_twig_bridge(): void {
+    // Guard: require parent TwigService and WooCommerce.
+    if ( ! class_exists( '\WPBootstrap\Twig\TwigService' ) || ! function_exists( 'WC' ) ) {
+        return;
+    }
+
+    $twig = \WPBootstrap\Twig\TwigService::getInstance();
+    $env  = $twig->getEnvironment();
+
+    // Add child theme templates directory to the Twig loader so {% include %}
+    // directives in Twig templates can find other child theme templates.
+    $loader = $env->getLoader();
+    if ( $loader instanceof \Twig\Loader\FilesystemLoader ) {
+        $template_dir = WC_BOOTSTRAP_PATH . 'templates';
+        if ( is_dir( $template_dir ) ) {
+            $loader->prependPath( $template_dir );
+        }
+    }
+
+    // Register WooCommerce functions and filters as Twig extensions.
+    $env->addExtension( new \WcBootstrap\Twig\WooCommerceExtension() );
+
+    // Register template interception hooks.
     $override = new \WcBootstrap\TemplateOverride();
     $override->register();
 }
-add_action( 'after_setup_theme', 'wc_bootstrap_register_template_override' );
+add_action( 'init', 'wc_bootstrap_init_twig_bridge', 20 );
 
 /**
  * Enqueue child theme styles.