Markdown handoff: include source and destination preview

A clean Markdown handoff contains the editable source, the intended publishing destination, and a rendered preview or screenshot. Note any site-specific syntax, embedded HTML restrictions, relative link behavior, or image paths. Ask the next reviewer to inspect headings, list nesting, code fences, and mobile layout before posting. A preview is not the source of truth for future edits; keeping the original Markdown prevents formatting from being lost during a copy-and-paste handoff.