refactor: create separate BLoCs for each screen with comprehensive tests

- Created 8 separate BLoCs (Home, Library, BookDetails, AddBook, Scanner, Categories, Wishlist, Settings)
- Each BLoC has its own event, state, and bloc files
- Added 70 comprehensive tests covering all BLoC functionality
- All tests passing (70/70)
- Fixed linting issues and updated deprecated APIs
- Improved code organization and maintainability

bookshelf_flutter/lib/bloc/library/library_event.dart

@@ -0,0 +1,28 @@
+import '../../models/models.dart';
+
+abstract class LibraryEvent {
+  const LibraryEvent();
+}
+
+class LoadBooks extends LibraryEvent {
+  const LoadBooks();
+}
+
+class SearchBooks extends LibraryEvent {
+  final String query;
+  const SearchBooks(this.query);
+}
+
+class BookSelected extends LibraryEvent {
+  final Book book;
+  const BookSelected(this.book);
+}
+
+class FilterByStatus extends LibraryEvent {
+  final BookStatus status;
+  const FilterByStatus(this.status);
+}
+
+class ClearFilters extends LibraryEvent {
+  const ClearFilters();
+}