feat: add sidebar and item list to catalog page, enable DEBUG mode for development

- Created `side-bar.html` and `item-list.html` fragments for catalog page layout
- Updated `catalog/index.html` to include sidebar and item list templates
- Added styles for catalog layout in `catalog.css`
- Enabled `DEBUG=True` in settings for local development
- Adjusted CSS in shipping and services for consistent spacing

templates/catalog/_fragments/item-list.html

@@ -0,0 +1,6 @@
+<main class="item-list">
+    {% for item in items %}
+        <h1>item</h1>
+    {% endfor %}
+
+</main>