refactor(list-item): improve layout system and remove implicit child composition

Refactor ListItem 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**

- Replace arbitrary child composition with explicit slots
- Improve left/right accessory APIs
- Standardize spacing and density
- Improve multiline layout behavior
- Improve virtualization friendliness

**Proposed API Direction**

Instead of:

`

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Prefer:

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**Performance Opportunities**

- Improve rendering in FlatList usage
- Memoize accessories
- Reduce layout passes
- Avoid child traversal

The issue names no implementation file or test; begin by locating the TypeScript ListItem component and reviewing its current usages, especially in FlatList. Compare the proposed explicit title, description, left, and right API with the existing children API, then establish coverage for spacing, multiline layout, platform behavior, and virtualization before considering the refactor complete.

Written by the indexing model from the issue text.