Comprehensive Sample App Enhancement with Layout Presets and UI Improvements

[ppth0608]

🎯 Summary

This PR significantly enhances the KarrotListKit sample app with comprehensive
layout examples, preset factory methods, and improved UI components. The changes
provide better documentation and demonstration of the framework's capabilities.

🚀 Key Improvements

Layout Presets (/Samples/Presets/)

• Extensions.swift: Convenient factory methods for common layout patterns
• HorizontalLayout.swift: Horizontal scrolling layout with configurable behavior
• VerticalGridLayout.swift: Grid layout with customizable column counts
• VerticalLayout.swift: Standard vertical layout for list content

New Sample Views

• HorizontalLayout Sample: Demonstrates continuous, group paging, and individual
  paging behaviors
• VerticalGridLayout Sample: Shows 2, 3, and 4 column grid layouts with
  emoji-based content
• MixedLayout Sample: Comprehensive example combining all layout types in a
  single view
• Enhanced VerticalLayout: Improved with colorful icons and card-style design

Simulator.Screen.Recording.-.iPhone.15.Pro.-.2025-07-22.at.16.20.18.mp4

[ppth0608]

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