Add selected state and hover background to Card
- Add `selected` prop: brand border (warm gold) + warm background tint (brand.50)
- Add hover background fill (neutral.50) for interactive cards
- Add 3 new card tokens: border.selected, background.hover, background.selected
- Add stories: Selected, OptionSelect (single-select), MultiSelect (toggle),
OnDifferentBackgrounds (white vs grey surface comparison)
- Informed by FA 1.0 Figma ListItemPurchaseOption pattern (node 2349:39505)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Richie
74ee0b87da