E3.1.1 Make the prompt state the ground #53

Part of: content icon normalize --ground auto keeps pale grounds opaque on dark-card families and blows the 300 KB budget (E3.1).

Task

Make the prompt state the ground

Subtasks

• Insert the family ground hex and "no vignette, texture, gradient, shadow or glow"
• Update references/art-direction.md

Definition of done

• Tests added or updated and CI green
• Docs updated when the command surface or output changes
• No private registry data, local paths or private repository names in fixtures or docs