feat: Card MD3 Expressive improvements

[pawelkata]

Motivation

Card was still on the Paper 5 model: a mode prop, arbitrary children composition, and no first-class support for Material 3 expressive states (hover, focus, press, drag) or emphasis tokens. This made it hard to build Cards that match the Material 3 spec — variant-driven container/outline/elevation colors, state layers, focus indicators, and motion — without consumers hand-rolling that behavior on top of View/Surface.

This PR rewrites Card around the Material 3 contract:

• Replaces mode + arbitrary children with an explicit variant (filled | elevated | outlined) and deterministic slots (media, header/title+subtitle+leading+trailing, content, actions).
• Adds a single actionable target model: a Card with an interaction handler becomes one accessible control with button semantics; a Card without one stays a neutral grouping container, leaving independent actions to its actions slot.
• Introduces Material state layers, keyboard focus indicators, hover/press/drag visuals, and animated elevation/outline transitions driven by a resolveCardVisuals token contract, including MD3-correct color tokens (surfaceContainerHighest for filled, outlineVariant for outlined borders) and real ripple/state-layer feedback via TouchableRipple instead of a bare Pressable.
• Publishes the v6 Card contract and a Paper 5 → 6 migration guide.

Related issue

Addresses #4929.

Screenshots / Videos

See the new "Expressive Card gallery" example (example/src/Examples/CardExample.tsx) for variants, states, shapes, and light/dark/platform verification, and CardRenderCountExample.tsx for the render-count regression check.

Test plan

• yarn jest — full suite passes (58 suites / 737 tests), including the rewritten Card, Card.tokens, and Surface unit tests covering variants, states (hover/press/focus/drag/disabled), shapes, accessibility, and motion.
• yarn typecheck — passes, including the new @ts-expect-error cases asserting the removed mode/children API is rejected at compile time.
• yarn lint — passes.
• Manually exercised the CardExample gallery in the example app (variants, custom headers, responsive cover media, disabled/dragged states, light/dark theme, platform-specific pressed/long-press messaging).