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/book_details/book_details_bloc.dart

@@ -0,0 +1,64 @@
+import 'package:flutter_bloc/flutter_bloc.dart';
+import '../../models/models.dart';
+import 'book_details_event.dart';
+import 'book_details_state.dart';
+
+class BookDetailsBloc extends Bloc<BookDetailsEvent, BookDetailsState> {
+  BookDetailsBloc() : super(BookDetailsState.initial()) {
+    on<LoadBookDetails>(_onLoadBookDetails);
+    on<ToggleFavorite>(_onToggleFavorite);
+    on<UpdateProgress>(_onUpdateProgress);
+    on<UpdateStatus>(_onUpdateStatus);
+    on<DeleteBook>(_onDeleteBook);
+  }
+
+  void _onLoadBookDetails(LoadBookDetails event, Emitter<BookDetailsState> emit) {
+    emit(state.copyWith(
+      book: event.book,
+      isLoading: false,
+    ));
+  }
+
+  void _onToggleFavorite(ToggleFavorite event, Emitter<BookDetailsState> emit) {
+    if (state.book == null) return;
+    
+    final updatedBook = state.book!.copyWith(
+      isFavorite: !state.book!.isFavorite,
+    );
+    
+    emit(state.copyWith(
+      book: updatedBook,
+    ));
+  }
+
+  void _onUpdateProgress(UpdateProgress event, Emitter<BookDetailsState> emit) {
+    if (state.book == null) return;
+    
+    final updatedBook = state.book!.copyWith(
+      progress: event.progress,
+      status: event.progress >= 100 ? BookStatus.done : BookStatus.reading,
+    );
+    
+    emit(state.copyWith(
+      book: updatedBook,
+    ));
+  }
+
+  void _onUpdateStatus(UpdateStatus event, Emitter<BookDetailsState> emit) {
+    if (state.book == null) return;
+    
+    final updatedBook = state.book!.copyWith(
+      status: event.status,
+    );
+    
+    emit(state.copyWith(
+      book: updatedBook,
+    ));
+  }
+
+  void _onDeleteBook(DeleteBook event, Emitter<BookDetailsState> emit) {
+    emit(state.copyWith(
+      isDeleted: true,
+    ));
+  }
+}