feat: implement pagination for CleanAPK search results

- Replace static list search with Paging 3 implementation for FOSS and PWA tabs
- Add `CleanApkSearchPagingRepository` and `CleanApkSearchPagingSource`
- Update `SearchViewModelV2` to expose paging flows instead of static lists
- Refactor `SearchResultsContent` and `SearchScreen` to use `LazyPagingItems`
- Add support for preserving scroll position across tabs
- Introduce new UI states: `SearchLoading` (shimmer), `SearchErrorState`, and specific `SearchInitialState`
- Update `CleanApkSearchHelper` to support paginated requests with page/limit parameters