Implement Phase 3: single product page templates (Bootstrap 5)

Add 21 Twig template overrides for the single product page:

Product layout:
- product-image: gallery with thumbnail strip, img-fluid rounded
- title: h1 entry-title
- price: fs-3 fw-bold with sale del/ins markup
- short-description: lead text-body-secondary
- meta: dl row with SKU, categories, tags
- rating: Bootstrap Icon stars with half-star, review count link
- stock: badge (bg-success/bg-danger/bg-warning) per status
- sale-flash: badge bg-danger fs-6
- share: hook-only wrapper
- product-attributes: table-sm table-striped

Related/upsells:
- related, up-sells: section with product loop grid

Tabs:
- tabs: nav-tabs + tab-content with fade transitions
- description: tab-pane with prose content
- additional-information: tab-pane with attributes hook

Add to cart (4 product types + variation JS):
- simple: input-group quantity + btn-primary btn-lg
- variable: form-select per attribute + variation display
- grouped: table-borderless with quantity per child product
- external: btn-outline-primary with external link icon
- variation: Underscore.js script templates (Bootstrap-styled)
- variation-add-to-cart-button: quantity + submit with hidden fields

CSS additions: gallery thumbnail hover, variation selector spacing.

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

templates/single-product/add-to-cart/variable.html.twig

@@ -0,0 +1,88 @@
+{#
+ # Variable Product Add to Cart (Bootstrap 5 Override)
+ #
+ # Add-to-cart form for variable products with attribute selectors.
+ #
+ # Expected context:
+ #   product              - WC_Product_Variable object
+ #   attributes           - Array of attribute taxonomies
+ #   available_variations - JSON-encoded variations data
+ #   attribute_keys       - Array of attribute keys
+ #   variations_json      - Variations data as JSON string
+ #   variations_attr      - Data attribute string for the form
+ #   selected_attributes  - Currently selected attribute values
+ #
+ # WooCommerce PHP equivalent: single-product/add-to-cart/variable.php
+ #
+ # @package WcBootstrap
+ # @since 0.1.0
+ #}
+
+{{ do_action('woocommerce_before_add_to_cart_form') }}
+
+<form class="variations_form cart"
+      action="{{ product.get_permalink()|esc_url }}"
+      method="post"
+      enctype="multipart/form-data"
+      {{ variations_attr|default('')|raw }}>
+
+    {{ do_action('woocommerce_before_variations_form') }}
+
+    {% if available_variations is defined %}
+        {# Variation attribute selectors #}
+        <div class="variations mb-4">
+            {% for attribute_name, options in attributes %}
+                <div class="mb-3">
+                    <label class="form-label fw-semibold" for="{{ attribute_name|esc_attr }}">
+                        {{ wc_attribute_label(attribute_name)|esc_html }}
+                    </label>
+                    <select id="{{ attribute_name|esc_attr }}"
+                            class="form-select"
+                            name="attribute_{{ attribute_name|esc_attr }}"
+                            data-attribute_name="attribute_{{ attribute_name|esc_attr }}">
+                        <option value="">{{ __('Choose an option') }}</option>
+                        {% if options is iterable %}
+                            {% for option in options %}
+                                {% set selected_value = selected_attributes[attribute_name]|default('') %}
+                                <option value="{{ option|esc_attr }}"{% if option == selected_value %} selected{% endif %}>
+                                    {{ option|esc_html }}
+                                </option>
+                            {% endfor %}
+                        {% endif %}
+                    </select>
+                </div>
+            {% endfor %}
+        </div>
+
+        {{ do_action('woocommerce_after_variations_table') }}
+
+        {# Reset link #}
+        <div class="reset_variations_wrapper mb-3" style="display: none;">
+            <a class="reset_variations btn btn-link btn-sm p-0 text-decoration-none" href="#">
+                {{ __('Clear') }}
+            </a>
+        </div>
+
+        {# Single variation display + add-to-cart button #}
+        <div class="single_variation_wrap">
+            {{ do_action('woocommerce_before_single_variation') }}
+
+            <div class="woocommerce-variation single_variation"></div>
+
+            <div class="woocommerce-variation-add-to-cart variations_button">
+                {{ do_action('woocommerce_single_variation') }}
+            </div>
+
+            {{ do_action('woocommerce_after_single_variation') }}
+        </div>
+    {% else %}
+        {# Out of stock / unavailable #}
+        <p class="stock out-of-stock alert alert-warning">
+            {{ __('This product is currently out of stock and unavailable.') }}
+        </p>
+    {% endif %}
+
+    {{ do_action('woocommerce_after_variations_form') }}
+</form>
+
+{{ do_action('woocommerce_after_add_to_cart_form') }}