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/home/home_bloc_test.dart

@@ -0,0 +1,85 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:bookshelf_flutter/bloc/home/home_bloc.dart';
+import 'package:bookshelf_flutter/bloc/home/home_event.dart';
+import 'package:bookshelf_flutter/bloc/home/home_state.dart';
+import 'package:bookshelf_flutter/models/models.dart';
+
+void main() {
+  group('HomeBloc', () {
+    late HomeBloc homeBloc;
+
+    setUp(() {
+      homeBloc = HomeBloc();
+    });
+
+    tearDown(() {
+      homeBloc.close();
+    });
+
+    test('initial state is HomeState.initial()', () {
+      expect(homeBloc.state, isA<HomeState>());
+      expect(homeBloc.state.isLoading, true);
+    });
+
+    group('LoadHomeData', () {
+      test('loads home data with default screen', () async {
+        homeBloc.add(const LoadHomeData());
+        await Future.delayed(Duration.zero);
+
+        expect(homeBloc.state.currentScreen, AppScreen.library);
+        expect(homeBloc.state.isLoading, false);
+      });
+    });
+
+    group('NavigateToScreen', () {
+      test('navigates to library screen', () async {
+        homeBloc.add(const NavigateToScreen(AppScreen.library));
+        await Future.delayed(Duration.zero);
+
+        expect(homeBloc.state.currentScreen, AppScreen.library);
+      });
+
+      test('navigates to categories screen', () async {
+        homeBloc.add(const NavigateToScreen(AppScreen.categories));
+        await Future.delayed(Duration.zero);
+
+        expect(homeBloc.state.currentScreen, AppScreen.categories);
+      });
+
+      test('navigates to wishlist screen', () async {
+        homeBloc.add(const NavigateToScreen(AppScreen.wishlist));
+        await Future.delayed(Duration.zero);
+
+        expect(homeBloc.state.currentScreen, AppScreen.wishlist);
+      });
+
+      test('navigates to settings screen', () async {
+        homeBloc.add(const NavigateToScreen(AppScreen.settings));
+        await Future.delayed(Duration.zero);
+
+        expect(homeBloc.state.currentScreen, AppScreen.settings);
+      });
+
+      test('navigates to details screen', () async {
+        homeBloc.add(const NavigateToScreen(AppScreen.details));
+        await Future.delayed(Duration.zero);
+
+        expect(homeBloc.state.currentScreen, AppScreen.details);
+      });
+
+      test('navigates to add book screen', () async {
+        homeBloc.add(const NavigateToScreen(AppScreen.addBook));
+        await Future.delayed(Duration.zero);
+
+        expect(homeBloc.state.currentScreen, AppScreen.addBook);
+      });
+
+      test('navigates to scanner screen', () async {
+        homeBloc.add(const NavigateToScreen(AppScreen.scanner));
+        await Future.delayed(Duration.zero);
+
+        expect(homeBloc.state.currentScreen, AppScreen.scanner);
+      });
+    });
+  });
+}