refactor(card): modernize composition model and improve MD3 behavior

Refactor Card to improve Material Design 3 compliance, remove problematic children patterns, improve performance characteristics, and modernize the public API.

**Problems**

- Current API relies heavily on children composition in ways that are difficult to optimize
- Internal layout logic is tightly coupled to arbitrary child structures
- MD3 behaviors and visuals are not fully aligned with current Material guidelines
- Rendering performance can degrade in large lists or frequently updated screens
- Type safety and discoverability of the API can be improved
- The component has inconsistent behavior between platforms and edge cases

**Focus Areas**

- Reduce dependence on deeply nested children
- Improve Card.Content / Card.Actions architecture
- Improve elevation and surface behavior
- Improve shape and outlined variants
- Simplify internal spacing rules

**Proposed API Direction**

Introduce clearer slot-based APIs:
`Content}
actions={[...]}
/>`

**Performance Opportunities**

- Reduce nested wrappers
- Optimize pressable behavior
- Avoid unnecessary subtree re-renders
- Improve memoization boundaries