Implement Phase 1: global templates and notices (Bootstrap 5)

Add 9 Twig template overrides for WooCommerce's global and notice templates:
- global/wrapper-start, wrapper-end: conditional container with _theme_wrapped
- global/breadcrumb: Bootstrap breadcrumb component with aria-current
- global/sidebar: offcanvas-lg for mobile, standard aside for desktop
- global/quantity-input: input-group with +/- buttons
- global/form-login: responsive form with form-control, form-check
- notices/notice, error, success: Bootstrap alert-dismissible with icons

Supporting changes:
- assets/js/quantity.js: +/- button handler respecting min/max/step
- assets/css/wc-bootstrap.css: WooCommerce notice fallback styles, spinner removal
- functions.php: register quantity.js script

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

functions.php

@@ -94,6 +94,25 @@ function wc_bootstrap_enqueue_styles(): void {
 }
 add_action( 'wp_enqueue_scripts', 'wc_bootstrap_enqueue_styles' );
 
+/**
+ * Enqueue child theme scripts.
+ *
+ * @since 0.1.0
+ */
+function wc_bootstrap_enqueue_scripts(): void {
+    $theme_version = wp_get_theme()->get( 'Version' );
+
+    // Quantity +/- button handler for Bootstrap input-group widget.
+    wp_enqueue_script(
+        'wc-bootstrap-quantity',
+        get_stylesheet_directory_uri() . '/assets/js/quantity.js',
+        array(),
+        $theme_version,
+        true
+    );
+}
+add_action( 'wp_enqueue_scripts', 'wc_bootstrap_enqueue_scripts' );
+
 /**
  * Handle plugin page rendering via plugin render filter.
  *