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>

templates/global/form-login.html.twig

@@ -0,0 +1,89 @@
+{#
+ # Global Login Form (Bootstrap 5 Override)
+ #
+ # Inline login form used on checkout and other pages (not the My Account login).
+ # Can be initially hidden and toggled via a link.
+ #
+ # Expected context (from WooCommerce wc_get_template('global/form-login.php')):
+ #   hidden   - Whether form is initially hidden (boolean)
+ #   message  - Optional message to display above the form
+ #   redirect - URL to redirect after login
+ #
+ # WooCommerce PHP equivalent: global/form-login.php
+ #
+ # @package WcBootstrap
+ # @since 0.1.0
+ #}
+
+{% if not is_user_logged_in() %}
+    <form class="woocommerce-form woocommerce-form-login login{% if hidden %} d-none{% endif %}" method="post">
+
+        {{ do_action('woocommerce_login_form_start') }}
+
+        {% if message %}
+            <div class="mb-3">
+                {{ message|wpautop }}
+            </div>
+        {% endif %}
+
+        <div class="row g-3 mb-3">
+            <div class="col-sm-6">
+                <label for="username" class="form-label">
+                    {{ __('Username or email') }}&nbsp;<span class="text-danger" aria-hidden="true">*</span>
+                    <span class="visually-hidden">{{ __('Required') }}</span>
+                </label>
+                <input type="text"
+                       class="form-control"
+                       name="username"
+                       id="username"
+                       autocomplete="username"
+                       required
+                       aria-required="true" />
+            </div>
+            <div class="col-sm-6">
+                <label for="password" class="form-label">
+                    {{ __('Password') }}&nbsp;<span class="text-danger" aria-hidden="true">*</span>
+                    <span class="visually-hidden">{{ __('Required') }}</span>
+                </label>
+                <input type="password"
+                       class="form-control"
+                       name="password"
+                       id="password"
+                       autocomplete="current-password"
+                       required
+                       aria-required="true" />
+            </div>
+        </div>
+
+        {{ do_action('woocommerce_login_form') }}
+
+        <div class="d-flex align-items-center justify-content-between flex-wrap gap-2">
+            <div class="form-check">
+                <input class="form-check-input"
+                       type="checkbox"
+                       name="rememberme"
+                       id="rememberme"
+                       value="forever" />
+                <label class="form-check-label" for="rememberme">
+                    {{ __('Remember me') }}
+                </label>
+            </div>
+
+            {{ wp_nonce_field('woocommerce-login', 'woocommerce-login-nonce') }}
+            <input type="hidden" name="redirect" value="{{ redirect|esc_url }}" />
+
+            <button type="submit"
+                    class="btn btn-primary"
+                    name="login"
+                    value="{{ __('Login') }}">
+                {{ __('Login') }}
+            </button>
+        </div>
+
+        <p class="mt-3 mb-0">
+            <a href="{{ wp_lostpassword_url()|esc_url }}">{{ __('Lost your password?') }}</a>
+        </p>
+
+        {{ do_action('woocommerce_login_form_end') }}
+    </form>
+{% endif %}