Add product category tree sidebar to archive and single product pages (v0.1.7)

Hierarchical category navigation with collapsible sub-levels up to 3 levels
deep, using Bootstrap 5 list-group and collapse components. Sidebar renders
on both archive/shop and single product pages with responsive offcanvas on
mobile. Active category highlighting and ancestor auto-expand for intuitive
navigation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

templates/global/category-tree.html.twig

@@ -0,0 +1,34 @@
+{#
+ # Product Category Tree (Bootstrap 5)
+ #
+ # Renders a hierarchical product category navigation with collapsible
+ # sub-levels, up to 3 levels deep. Uses Bootstrap 5 list-group and
+ # collapse components for responsive tree navigation.
+ #
+ # Expected context:
+ #   categories - Hierarchical array from wc_bootstrap_get_category_tree()
+ #   shop_url   - URL to the main shop page
+ #
+ # @package WcBootstrap
+ # @since 0.1.7
+ #}
+
+{% if categories is not empty %}
+<nav aria-label="{{ __('Product categories', 'wc-bootstrap') }}">
+    <h3 class="sidebar-heading h6 text-uppercase fw-semibold">
+        {{ __('Categories', 'wc-bootstrap') }}
+    </h3>
+
+    <ul class="list-group list-group-flush category-tree">
+        <li class="list-group-item px-0 py-1">
+            <a href="{{ shop_url }}"
+               class="category-tree-link d-block text-decoration-none py-1 px-2 rounded{% if current_cat == 0 %} active fw-semibold{% endif %}">
+                {{ __('All products', 'wc-bootstrap') }}
+            </a>
+        </li>
+        {% for cat in categories %}
+            {% include 'global/category-tree-node.html.twig' with { node: cat, level: 1 } only %}
+        {% endfor %}
+    </ul>
+</nav>
+{% endif %}