Implement Phase 4 & 5: cart and checkout templates (Bootstrap 5, HPOS)

Phase 4 - Cart (9 templates):
- cart: 8+4 column layout, table-responsive items, coupon input-group
- cart-empty: centered empty state with cart-x icon
- cart-item-data: inline dl for variation details
- cart-totals: card with list-group-flush rows, sticky sidebar
- cart-shipping: form-check radio per shipping method
- cross-sells: product loop grid section
- mini-cart: offcanvas-compatible item list with remove buttons
- proceed-to-checkout-button: btn-primary btn-lg w-100
- shipping-calculator: collapsible form with form-select/form-control

Phase 5 - Checkout (12 templates):
- form-checkout: 7+5 column layout, sticky order review sidebar
- form-billing: card with field wrapper, optional account creation
- form-shipping: card with ship-to-different-address collapse toggle
- form-coupon: collapsible input-group with alert-info toggle
- form-login: collapsible login reusing global/form-login.html.twig
- review-order: card with table-sm, tfoot subtotal/shipping/total
- payment: list-group of payment gateways with radio selection
- payment-method: form-check with description collapse
- terms: form-check checkbox with T&C link
- thankyou: HPOS compatible, alert-success + order details list-group
- order-received: confirmation message
- cart-errors: alert-danger with return-to-cart button

All order data accessed via WC_Order methods (HPOS compatible).
CSS additions: cart thumbnail sizing, checkout form field overrides,
payment box transitions, dark mode focus states.

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

templates/checkout/thankyou.html.twig

@@ -0,0 +1,75 @@
+{#
+ # Thank You / Order Confirmation (Bootstrap 5 Override)
+ #
+ # HPOS compatible: uses WC_Order object methods only, no $post global.
+ #
+ # Expected context:
+ #   order - WC_Order object (or null on failure)
+ #
+ # WooCommerce PHP equivalent: checkout/thankyou.php
+ #
+ # @package WcBootstrap
+ # @since 0.1.0
+ #}
+
+{{ do_action('woocommerce_before_thankyou') }}
+
+{% if order is defined and order %}
+    {% if order.has_status('failed') %}
+        <div class="alert alert-danger mb-4" role="alert">
+            <p class="mb-0">
+                {{ __('Unfortunately your order cannot be processed as the originating bank/merchant has declined your transaction. Please attempt your purchase again.') }}
+            </p>
+        </div>
+        <p>
+            <a href="{{ order.get_checkout_payment_url()|esc_url }}" class="btn btn-outline-primary">
+                {{ __('Pay') }}
+            </a>
+        </p>
+    {% else %}
+        <div class="alert alert-success mb-4" role="alert">
+            <i class="bi bi-check-circle me-2" aria-hidden="true"></i>
+            {% include 'checkout/order-received.html.twig' with { order: order } %}
+        </div>
+
+        <div class="card shadow-sm mb-4">
+            <div class="card-header">
+                <h2 class="h5 mb-0">{{ __('Order details') }}</h2>
+            </div>
+            <ul class="list-group list-group-flush">
+                <li class="list-group-item d-flex justify-content-between">
+                    <span class="text-body-secondary">{{ __('Order number:') }}</span>
+                    <strong>{{ order.get_order_number() }}</strong>
+                </li>
+                <li class="list-group-item d-flex justify-content-between">
+                    <span class="text-body-secondary">{{ __('Date:') }}</span>
+                    <strong>{{ order.get_date_created().date_i18n(wc_date_format()) }}</strong>
+                </li>
+                {% if order.get_billing_email() %}
+                    <li class="list-group-item d-flex justify-content-between">
+                        <span class="text-body-secondary">{{ __('Email:') }}</span>
+                        <strong>{{ order.get_billing_email()|esc_html }}</strong>
+                    </li>
+                {% endif %}
+                <li class="list-group-item d-flex justify-content-between">
+                    <span class="text-body-secondary">{{ __('Total:') }}</span>
+                    <strong>{{ order.get_formatted_order_total()|raw }}</strong>
+                </li>
+                {% if order.get_payment_method_title() %}
+                    <li class="list-group-item d-flex justify-content-between">
+                        <span class="text-body-secondary">{{ __('Payment method:') }}</span>
+                        <strong>{{ order.get_payment_method_title()|esc_html }}</strong>
+                    </li>
+                {% endif %}
+            </ul>
+        </div>
+    {% endif %}
+
+    {{ do_action('woocommerce_thankyou_' ~ order.get_payment_method(), order.get_id()) }}
+    {{ do_action('woocommerce_thankyou', order.get_id()) }}
+{% else %}
+    <div class="alert alert-success mb-4" role="alert">
+        <i class="bi bi-check-circle me-2" aria-hidden="true"></i>
+        {% include 'checkout/order-received.html.twig' %}
+    </div>
+{% endif %}