Fix product images, add-to-cart, and add Sub Categories filter

- Add display:block to .product-card-image so padding-top aspect ratio works on anchor tags
- Add Cache-Control: no-transform header to disable Cloudflare Rocket Loader (was deferring main.js and breaking add-to-cart click handlers)
- Add Sub Categories filter row on shop page using product_types table
- Show category · sub-category on product cards
- Add Sub Categories section to footer
- Preserve subcat param across category/sort filter links

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

includes/footer.php

@@ -23,6 +23,17 @@
                         <li><a href="/shop.php?category=blends">Blends</a></li>
                     </ul>
                 </div>
+
+                <div>
+                    <h4>Sub Categories</h4>
+                    <ul class="footer-links">
+                        <?php
+                        $footerTypes = db()->fetchAll("SELECT type_id, name FROM product_types WHERE is_active=1 ORDER BY sort_order ASC");
+                        foreach ($footerTypes as $ft): ?>
+                            <li><a href="/shop.php?subcat=<?= urlencode($ft['type_id']) ?>"><?= htmlspecialchars($ft['name']) ?></a></li>
+                        <?php endforeach; ?>
+                    </ul>
+                </div>
                 
                 <div>
                     <h4>Company</h4>

includes/header.php

@@ -6,6 +6,7 @@
 if (session_status() === PHP_SESSION_NONE) {
     session_start();
 }
+header('Cache-Control: no-store, no-cache, must-revalidate, no-transform');
 
 require_once __DIR__ . '/db.php';
 require_once __DIR__ . '/../config/config.php';