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/test/bloc/library/library_bloc_test.dart

@@ -0,0 +1,124 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:bookshelf_flutter/bloc/library/library_bloc.dart';
+import 'package:bookshelf_flutter/bloc/library/library_event.dart';
+import 'package:bookshelf_flutter/bloc/library/library_state.dart';
+import 'package:bookshelf_flutter/models/models.dart';
+
+void main() {
+  group('LibraryBloc', () {
+    late LibraryBloc libraryBloc;
+
+    setUp(() {
+      libraryBloc = LibraryBloc();
+    });
+
+    tearDown(() {
+      libraryBloc.close();
+    });
+
+    test('initial state is LibraryState.initial()', () {
+      expect(libraryBloc.state, isA<LibraryState>());
+      expect(libraryBloc.state.isLoading, true);
+    });
+
+    group('LoadBooks', () {
+      test('emits [LibraryState] with books when LoadBooks is added', () async {
+        final expected = [
+          isA<LibraryState>()
+              .having((state) => state.isLoading, 'isLoading', false)
+              .having((state) => state.books.isNotEmpty, 'books.isNotEmpty', true),
+        ];
+
+        expectLater(libraryBloc.stream, emitsInOrder(expected));
+
+        libraryBloc.add(const LoadBooks());
+      });
+    });
+
+    group('SearchBooks', () {
+      test('filters books by title', () async {
+        libraryBloc.add(const LoadBooks());
+        await Future.delayed(Duration.zero);
+
+        libraryBloc.add(const SearchBooks('Гэтсби'));
+        await Future.delayed(Duration.zero);
+
+        expect(libraryBloc.state.filteredBooks.length, 1);
+        expect(libraryBloc.state.filteredBooks.first.title, contains('Гэтсби'));
+      });
+
+      test('filters books by author', () async {
+        libraryBloc.add(const LoadBooks());
+        await Future.delayed(Duration.zero);
+
+        libraryBloc.add(const SearchBooks('Оруэлл'));
+        await Future.delayed(Duration.zero);
+
+        expect(libraryBloc.state.filteredBooks.length, 1);
+        expect(libraryBloc.state.filteredBooks.first.author, contains('Оруэлл'));
+      });
+
+      test('filters books by genre', () async {
+        libraryBloc.add(const LoadBooks());
+        await Future.delayed(Duration.zero);
+
+        libraryBloc.add(const SearchBooks('Fantasy'));
+        await Future.delayed(Duration.zero);
+
+        expect(libraryBloc.state.filteredBooks.isNotEmpty, true);
+      });
+
+      test('returns empty list when no matches found', () async {
+        libraryBloc.add(const LoadBooks());
+        await Future.delayed(Duration.zero);
+
+        libraryBloc.add(const SearchBooks('NonExistent'));
+        await Future.delayed(Duration.zero);
+
+        expect(libraryBloc.state.filteredBooks.length, 0);
+      });
+    });
+
+    group('BookSelected', () {
+      test('updates selectedBook in state', () async {
+        libraryBloc.add(const LoadBooks());
+        await Future.delayed(Duration.zero);
+
+        final book = libraryBloc.state.books.first;
+        libraryBloc.add(BookSelected(book));
+        await Future.delayed(Duration.zero);
+
+        expect(libraryBloc.state.selectedBook?.id, book.id);
+      });
+    });
+
+    group('FilterByStatus', () {
+      test('filters books by status', () async {
+        libraryBloc.add(const LoadBooks());
+        await Future.delayed(Duration.zero);
+
+        libraryBloc.add(const FilterByStatus(BookStatus.reading));
+        await Future.delayed(Duration.zero);
+
+        expect(libraryBloc.state.filteredBooks.every((book) => book.status == BookStatus.reading), true);
+        expect(libraryBloc.state.statusFilter, BookStatus.reading);
+      });
+    });
+
+    group('ClearFilters', () {
+      test('clears search query and shows all books', () async {
+        libraryBloc.add(const LoadBooks());
+        await Future.delayed(Duration.zero);
+
+        libraryBloc.add(const SearchBooks('test'));
+        await Future.delayed(Duration.zero);
+
+        libraryBloc.add(const ClearFilters());
+        await Future.delayed(Duration.zero);
+
+        expect(libraryBloc.state.searchQuery, '');
+        expect(libraryBloc.state.filteredBooks.length, libraryBloc.state.books.length);
+      });
+    });
+  });
+}