fix: Message recycling bug with FlashList

[edgarpavlovsky]

This pull request introduces a comprehensive chat list test screen for the React Native debugger app, focusing on improving the reliability of chat message rendering and providing tools to debug list recycling issues. It also updates dependencies and enhances the test data for chat messages, including streaming and image-rich content. The most important changes are grouped below.

Chat List Testing & Debugging:

• Added a new ChatTestScreen component that allows testing chat message rendering with both FlashList and LegendList, supporting toggling between Streamdown and Markdown render modes, simulating streaming assistant responses, and displaying message debug info for recycling validation.
• Introduced a ListPickerScreen for selecting which list implementation to test from the main app screen, and refactored the app mode state to support multiple test screens. (Ffd0e18fL13R13, [1] [2]

Test Data Improvements:

• Created a new testMessages.ts data module with realistic, image-rich, and code-block-containing chat messages, as well as helpers for generating user and assistant messages with streaming support and debug numbering.

Bug Fixes & Dependency Updates:

• Fixed a FlashList v2 bug where recycled cells could render incorrect content by ensuring message content and registry state are correctly reset, and added an AutoSizedImage component for image aspect ratio accuracy.
• Updated package.json dependencies to include @shopify/flash-list and react-native-markdown-display for improved list and markdown rendering. [1] [2]

UI/UX Improvements:

• Enhanced styles for mode switching, input, and chat message display for better usability and visual clarity.

These changes provide a robust environment for testing and debugging chat UI rendering and list recycling issues in React Native.

Fixes issue #9