Add responsive image optimization with WebP support

- Configure thumbs presets in config.php (quality 85%, WebP format)
- Create picture snippet with srcset and WebP support
- Add product-card and product-detail presets
- Update templates to use optimized images
- Implement native lazy loading for product cards
- Add aspect-ratio CSS for layout stability

Improvements over reference project:
- Complete PHPDoc documentation
- Native CSS aspect-ratio support
- Optimized lazy loading strategy
- Product-specific image presets

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

site/templates/home.php

@@ -10,7 +10,13 @@
             <article class="store__product">
                 <figure>
                     <?php if($image = $product->images()->first()): ?>
-                        <img src="<?= $image->url() ?>" alt="<?= $product->title()->html() ?>" />
+                        <?php snippet('picture', [
+                            'file' => $image,
+                            'alt' => $product->title()->html(),
+                            'preset' => 'product-card',
+                            'size' => 25,
+                            'lazy' => true
+                        ]) ?>
                     <?php endif ?>
                 </figure>
                 <p class="line-1"><a href="<?= $product->url() ?>"><?= $product->title()->html() ?></a></p>