fix(ai-help): Example header highlighting

[argl]

Summary

This fixes an issue on example queues from either the AI help section or the blog section. In some situations, the mouse-over highlight of the example, triggered from the playground queue did not survive a scroll-into-view.

Problem

The highlight css attribute got set directly on the element from the mouse event handler. Therefore it did not survive a react re-render of the component. A render is sometimes triggered by the autmatic viewport scrolling.

Solution

Refactored the highlighting into a react state variable that is part of the UI context and properly tracked. The playground queue is currently used in the AI-help section and in the Blog section (to my knowledge).

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How did you test this change?

Manually, locally