Add description field to Product model

Issue: The landing page template supported displaying product descriptions,
but the Product model didn't load the description field from config.yaml files.

Changes:
- Added optional 'description' parameter to Product.__init__()
- Updated Product.to_dict() to include description (if present)
- Updated Product.from_dict() to load description from config
- Added test to verify descriptions are displayed on landing page

All 9 landing page tests passing.

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

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

tests/contract/test_landing_routes.py

@@ -180,3 +180,34 @@ def test_landing_page_with_authenticated_user_renders_correctly(client, test_pro
     # Should contain products (proving the page rendered successfully)
     assert b'Apple Product' in response.data
     assert b'Zebra Product' in response.data
+
+
+@pytest.mark.contract
+def test_landing_page_displays_product_descriptions(client, test_products):
+    """Test that product descriptions from config.yaml are displayed on landing page
+
+    This test verifies that when a product has a description field in its config.yaml,
+    that description is properly loaded by the Product model and displayed on the landing page.
+    """
+    response = client.get('/')
+
+    assert response.status_code == 200
+
+    # Zebra Product has a description in the fixture
+    assert b'Zebra Product' in response.data
+    assert b'A product for testing' in response.data
+
+    # Apple Product has no description - should not show any placeholder
+    assert b'Apple Product' in response.data
+    # No description text should appear for Apple Product
+    html = response.data.decode('utf-8')
+
+    # Verify Zebra description is present
+    assert 'A product for testing' in html
+
+    # Verify the description appears between the product name and the submit button
+    zebra_section_start = html.find('Zebra Product')
+    zebra_section_end = html.find('Submit Feedback', zebra_section_start)
+    zebra_section = html[zebra_section_start:zebra_section_end]
+
+    assert 'A product for testing' in zebra_section