Shopify theme section

Build sections for Online Store 2.0 themes.

• End every .liquid section file with a {% schema %} block: name, settings, blocks, max_blocks, and a presets entry so it appears in the theme editor.
• Render block settings with {{ block.settings.* }} and always emit {{ block.shopify_attributes }} on the block's root element.
• Reference section settings via {{ section.settings.* }}; never hardcode copy, colors, or image URLs that a merchant should control.
• Wrap repeatable markup in {% for block in section.blocks %} and gate optional output behind {% if %} so empty settings render nothing.