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/add_book/add_book_bloc.dart

@@ -0,0 +1,110 @@
+import 'package:flutter_bloc/flutter_bloc.dart';
+import '../../models/models.dart';
+import 'add_book_event.dart';
+import 'add_book_state.dart';
+
+class AddBookBloc extends Bloc<AddBookEvent, AddBookState> {
+  AddBookBloc() : super(AddBookState.initial()) {
+    on<InitializeForm>(_onInitializeForm);
+    on<UpdateFormField>(_onUpdateFormField);
+    on<ToggleFavorite>(_onToggleFavorite);
+    on<ClearForm>(_onClearForm);
+    on<SubmitBook>(_onSubmitBook);
+  }
+
+  void _onInitializeForm(InitializeForm event, Emitter<AddBookState> emit) {
+    emit(state.copyWith(
+      prefilledData: event.prefilledData,
+      isLoading: false,
+    ));
+
+    if (event.prefilledData != null) {
+      final data = event.prefilledData!;
+      emit(state.copyWith(
+        title: data['title'] as String? ?? '',
+        author: data['author'] as String? ?? '',
+        genre: data['genre'] as String? ?? '',
+        annotation: data['annotation'] as String? ?? '',
+        coverUrl: data['coverUrl'] as String? ?? '',
+        pages: data['pages'] as int?,
+        language: data['language'] as String? ?? '',
+        publishedYear: data['publishedYear'] as int?,
+        rating: data['rating'] as double? ?? 0.0,
+        status: data['status'] as BookStatus? ?? BookStatus.wantToRead,
+        progress: data['progress'] as int? ?? 0,
+        isFavorite: data['isFavorite'] as bool? ?? false,
+      ));
+    }
+  }
+
+  void _onUpdateFormField(UpdateFormField event, Emitter<AddBookState> emit) {
+    switch (event.field) {
+      case 'title':
+        emit(state.copyWith(title: event.value as String));
+        break;
+      case 'author':
+        emit(state.copyWith(author: event.value as String));
+        break;
+      case 'genre':
+        emit(state.copyWith(genre: event.value as String));
+        break;
+      case 'annotation':
+        emit(state.copyWith(annotation: event.value as String));
+        break;
+      case 'coverUrl':
+        emit(state.copyWith(coverUrl: event.value as String));
+        break;
+      case 'pages':
+        emit(state.copyWith(pages: event.value as int?));
+        break;
+      case 'language':
+        emit(state.copyWith(language: event.value as String));
+        break;
+      case 'publishedYear':
+        emit(state.copyWith(publishedYear: event.value as int?));
+        break;
+      case 'rating':
+        emit(state.copyWith(rating: event.value as double?));
+        break;
+      case 'status':
+        emit(state.copyWith(status: event.value as BookStatus));
+        break;
+      case 'progress':
+        emit(state.copyWith(progress: event.value as int?));
+        break;
+    }
+  }
+
+  void _onToggleFavorite(ToggleFavorite event, Emitter<AddBookState> emit) {
+    emit(state.copyWith(isFavorite: !state.isFavorite));
+  }
+
+  void _onClearForm(ClearForm event, Emitter<AddBookState> emit) {
+    emit(AddBookState.initial());
+  }
+
+  void _onSubmitBook(SubmitBook event, Emitter<AddBookState> emit) {
+    final book = createBook(
+      id: DateTime.now().millisecondsSinceEpoch.toString(),
+      title: state.title.isNotEmpty ? state.title : 'Unknown',
+      author: state.author.isNotEmpty ? state.author : 'Unknown',
+      genre: state.genre.isNotEmpty ? state.genre : 'Unknown',
+      annotation: state.annotation,
+      coverUrl: state.coverUrl.isNotEmpty
+          ? state.coverUrl
+          : 'https://picsum.photos/seed/${DateTime.now().millisecondsSinceEpoch}/400/600',
+      pages: state.pages,
+      language: state.language,
+      publishedYear: state.publishedYear,
+      rating: state.rating,
+      status: state.status,
+      progress: state.progress,
+      isFavorite: state.isFavorite,
+    );
+
+    emit(state.copyWith(
+      submittedBook: book,
+      isSubmitted: true,
+    ));
+  }
+}