Update App.tsx

[imsharukh1994]

Summary of Changes:

1. Optimized Dependencies:

Used useCallback for handleAppStateChange to memoize it.
Cleaned up useEffect dependencies to avoid unnecessary re-renders.

2. Error Handling:

Added more specific error logging for chat loading.

3. Code Simplification:**

Destructured classes for cleaner JSX.
Moved inline components into variables for better readability.

4. Dynamic Theming:**

Assigned the theme based on feature flags.

5. Accessibility Improvements:**

Added aria-label for accessibility.
Feel free to adjust any of these improvements based on your specific requirements or project needs.

[imsharukh1994]

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[glahaye]

Thanks for the improvements!