Builds a Google-compliant ItemList JSON-LD block with correct position fields. Supports four list flavors — Summary, Article, Product, and Course — and outputs the full Carousel pattern when multiple items qualify for rich results.
One per line. Format depends on type:
• Summary: https://url or https://url | Item name
• Article: https://url | Title | Author | https://image.jpg
• Product: https://url | Name | Brand | Price | Currency | https://image.jpg
• Course: https://url | Name | Provider | Description