refactor(list-item): improve layout system and remove implicit child composition #4930

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:

<List.Item> <CustomContent /> </List.Item>

Prefer:

<List.Item title="Title" description="Description" left={...} right={...} />

Performance Opportunities

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