Add Bootstrap 5 single product page layout

Add two-column responsive grid (image gallery + product summary) for
single product pages, following the same bridge pattern used for
product archives.

Key changes:
- Create content-single-product.php bridge and Twig layout template
- Add single product renderer at template_redirect priority 11
- Disable WooCommerce block compatibility layer that strips classic
  hooks when parent theme has theme.json
- Move PHP templates to woocommerce/ subfolder for cleaner structure
- Fix Twig templates to self-compute context data not passed by
  wc_get_template() (tabs, short-description, meta, rating)
- Fix Underscore.js triple-brace syntax conflict in variation template
  by wrapping in {% verbatim %}

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

templates/single-product/rating.html.twig

@@ -4,10 +4,7 @@
  # Renders the star rating with review count link on the single product page.
  #
  # Expected context:
- #   product       - WC_Product object
- #   rating_count  - Number of ratings
- #   review_count  - Number of reviews
- #   average       - Average rating (0-5)
+ #   product - WC_Product object (from TemplateOverride)
  #
  # WooCommerce PHP equivalent: single-product/rating.php
  #
@@ -15,7 +12,17 @@
  # @since 0.1.0
  #}
 
-{% if rating_count is defined and rating_count > 0 %}
+{# Guard: bail if ratings are disabled. #}
+{% if fn('wc_review_ratings_enabled') %}
+
+{# Compute rating data from product object when not passed as context. #}
+{% if rating_count is not defined %}
+    {% set rating_count = product.get_rating_count() %}
+    {% set review_count = product.get_review_count() %}
+    {% set average = product.get_average_rating() %}
+{% endif %}
+
+{% if rating_count > 0 %}
     <div class="woocommerce-product-rating d-flex align-items-center gap-2 mb-3">
         <div class="wc-star-rating d-flex align-items-center gap-1"
              role="img"
@@ -31,10 +38,12 @@
             {% endfor %}
         </div>
 
-        {% if review_count is defined and review_count > 0 %}
+        {% if review_count > 0 %}
             <a href="#reviews" class="woocommerce-review-link text-body-secondary text-decoration-none small" rel="nofollow">
-                {{ _n('%s customer review', '%s customer reviews', review_count)|format(review_count) }}
+                {{ fn('_n', '%s customer review', '%s customer reviews', review_count, 'woocommerce')|format(review_count) }}
             </a>
         {% endif %}
     </div>
 {% endif %}
+
+{% endif %}{# wc_review_ratings_enabled #}