📜 refactor: Optimize Longer Message Thread Performance

[danny-avila]

I implemented several improvements to enhance the performance of long message threads and refactored related components. These changes resolve a long standing problem for the application from legacy code.

• Refactored the Markdown component to accept more specific props, reducing the need for context lookups within the component.
• Implemented useMemo hooks in MessageContent and Part components to optimize cursor and latest message calculations.
• Removed redundant components (Markdown.tsx and MessageContent.tsx) from the Messages/Content directory, consolidating functionality into the Chat/Messages/Content directory.
• Improved type safety and null checks throughout the codebase, particularly in the validateIframe utility function.
• Simplified conditional rendering logic in the Markdown component, making it more readable and maintainable.
• Updated import statements and component references to reflect the new structure and removed components.

Overall, the "after" state shows significant improvements in duration, render time, and passive effects.

Before

After

Checklist

• My code adheres to this project's style guidelines
• I have performed a self-review of my own code
• I have commented in any complex areas of my code
• My changes do not introduce new warnings
• I have tested my changes thoroughly
• Local unit tests pass with my changes