Cleanup.

[polina-c]

No description provided.

[gemini-code-assist]

Code Review

This pull request is a nice cleanup that refactors how widgets are built from the catalog. By introducing CatalogItemContext, the buildWidget method signature is simplified, and the parameters for widget building are neatly encapsulated. This improves code readability and maintainability. The consistent renaming of the context parameter to itemContext in all widget builders is also a great change that avoids potential confusion with Flutter's BuildContext.

I found one small area for further simplification in the catalog.dart file, which I've commented on. Overall, this is a solid improvement to the codebase.

[gemini-code-assist]

The logic for wrapping itemContext.buildChild is redundant. The buildChild function provided in itemContext (which originates from _GenUiSurfaceState._buildWidget) already handles the case where childDataContext is null by defaulting to the parent's dataContext. You can simplify this by passing itemContext.buildChild directly, which makes the code cleaner and avoids an unnecessary closure.

Suggested change

	buildChild: (String childId, [DataContext? childDataContext]) =>
	buildChild(childId, childDataContext ?? dataContext),
	dispatchEvent: dispatchEvent,
	buildContext: context,
	dataContext: dataContext,
	getComponent: getComponent,
	surfaceId: surfaceId,
	itemContext.buildChild(
	childId,
	childDataContext ?? itemContext.dataContext,
	),
	buildChild: itemContext.buildChild,