GameCardItem declares id: string! but the atom's own render-ui never passed
it through — GameCard.tsx requires id (used for the click payload
{cardId: id}), so orb validate correctly flagged ORB_RUI_MISSING_REQUIRED_PROP
on every board consuming this atom. Sibling atoms with the same
entity XItem { id } pattern (e.g. ChoiceButton) don't need this because their
React component has no required id prop — this is game-card-specific, not a
general atom convention gap. Added `id: @entity.id`; orb validate now 0/0.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>