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/wishlist/wishlist_bloc_test.dart

@@ -0,0 +1,104 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:bookshelf_flutter/bloc/wishlist/wishlist_bloc.dart';
+import 'package:bookshelf_flutter/bloc/wishlist/wishlist_event.dart';
+import 'package:bookshelf_flutter/bloc/wishlist/wishlist_state.dart';
+import 'package:bookshelf_flutter/models/models.dart';
+
+void main() {
+  group('WishlistBloc', () {
+    late WishlistBloc wishlistBloc;
+
+    setUp(() {
+      wishlistBloc = WishlistBloc();
+    });
+
+    tearDown(() {
+      wishlistBloc.close();
+    });
+
+    test('initial state is WishlistState.initial()', () {
+      expect(wishlistBloc.state, isA<WishlistState>());
+      expect(wishlistBloc.state.isLoading, true);
+    });
+
+    group('LoadWishlist', () {
+      test('loads wishlist books into state', () async {
+        wishlistBloc.add(const LoadWishlist());
+        await Future.delayed(Duration.zero);
+
+        expect(wishlistBloc.state.books.isNotEmpty, true);
+        expect(wishlistBloc.state.filteredBooks.isNotEmpty, true);
+        expect(wishlistBloc.state.isLoading, false);
+      });
+    });
+
+    group('RemoveFromWishlist', () {
+      test('removes book from both lists', () async {
+        wishlistBloc.add(const LoadWishlist());
+        await Future.delayed(Duration.zero);
+
+        final bookId = wishlistBloc.state.books.first.id;
+        wishlistBloc.add(RemoveFromWishlist(bookId));
+        await Future.delayed(Duration.zero);
+
+        expect(
+          wishlistBloc.state.books.any((book) => book.id == bookId),
+          false,
+        );
+        expect(
+          wishlistBloc.state.filteredBooks.any((book) => book.id == bookId),
+          false,
+        );
+      });
+    });
+
+    group('SearchWishlist', () {
+      test('filters books by title', () async {
+        wishlistBloc.add(const LoadWishlist());
+        await Future.delayed(Duration.zero);
+
+        wishlistBloc.add(const SearchWishlist('1984'));
+        await Future.delayed(Duration.zero);
+
+        expect(wishlistBloc.state.filteredBooks.length, 1);
+        expect(wishlistBloc.state.filteredBooks.first.title, contains('1984'));
+      });
+
+      test('filters books by author', () async {
+        wishlistBloc.add(const LoadWishlist());
+        await Future.delayed(Duration.zero);
+
+        wishlistBloc.add(const SearchWishlist('Оруэлл'));
+        await Future.delayed(Duration.zero);
+
+        expect(wishlistBloc.state.filteredBooks.length, 1);
+        expect(wishlistBloc.state.filteredBooks.first.author, contains('Оруэлл'));
+      });
+
+      test('returns empty list when no matches found', () async {
+        wishlistBloc.add(const LoadWishlist());
+        await Future.delayed(Duration.zero);
+
+        wishlistBloc.add(const SearchWishlist('NonExistent'));
+        await Future.delayed(Duration.zero);
+
+        expect(wishlistBloc.state.filteredBooks.length, 0);
+      });
+    });
+
+    group('MoveToLibrary', () {
+      test('updates book status to reading', () async {
+        wishlistBloc.add(const LoadWishlist());
+        await Future.delayed(Duration.zero);
+
+        final bookId = wishlistBloc.state.books.first.id;
+        wishlistBloc.add(MoveToLibrary(bookId));
+        await Future.delayed(Duration.zero);
+
+        final book = wishlistBloc.state.books.firstWhere((b) => b.id == bookId);
+        expect(book.status, BookStatus.reading);
+        expect(wishlistBloc.state.movedBookId, bookId);
+      });
+    });
+  });
+}