- Add BaseManager/CachedManager base classes to eliminate duplicate cache logic
- Add postListSources.ts with IPostListPagedSource interface
- Add groupListSources.ts with IGroupListPagedSource interface
- Refactor postManager to use CachedManager and Sources pattern
- Refactor groupManager to use CachedManager and Sources pattern
- Clean up duplicate methods in groupService.ts
- Fix TypeScript errors and remove mock data
- Introduced href functions for accessing materials, including hrefMaterials, hrefMaterialSubject, and hrefMaterialDetail.
- Updated AppsScreen to include a new entry for materials, enhancing the app's educational resources section.
- Exported material types in index.ts to support the new materials functionality.
