Reduce recompositions on search screen

[ivk1800]

What I have done and why

I refactored the SearchRoute → SearchScreen → SearchToolbar → SearchTextField chain to reduce unnecessary recompositions when the search query changes.

Before: entering a search query triggered recomposition of
SearchRoute, SearchScreen, SearchToolbar, SearchTextField, EmptySearchResultBody, RecentSearchesBody.

After: only SearchTextField and EmptySearchResultBody are recomposed.
SearchRoute, SearchScreen, and SearchToolbar stay stable.

This was achieved by:

1. Passing State instead of raw String as a parameter down the composable chain.
2. Adapting previews accordingly.

The approach is similar to this recomposition visualization(before) and this one (after).
In the "before" example, intermediate functions get recomposed unnecessarily because they take a changing value as a parameter. In the "after" example, they take a stable lambda, so only the leaf node (RedBox) is recomposed.

Why:

1. Reduces the number of recompositions.
2. Improves performance by keeping intermediate composables stable.

I followed the official Compose best practice — “Defer reads as long as possible” (see Android Performance Best Practices) — by deferring access to changing data until it’s needed, thus avoiding unnecessary recompositions.