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_event.dart

@@ -0,0 +1,28 @@
+import '../../models/models.dart';
+
+abstract class BookDetailsEvent {
+  const BookDetailsEvent();
+}
+
+class LoadBookDetails extends BookDetailsEvent {
+  final Book book;
+  const LoadBookDetails(this.book);
+}
+
+class ToggleFavorite extends BookDetailsEvent {
+  const ToggleFavorite();
+}
+
+class UpdateProgress extends BookDetailsEvent {
+  final int progress;
+  const UpdateProgress(this.progress);
+}
+
+class UpdateStatus extends BookDetailsEvent {
+  final BookStatus status;
+  const UpdateStatus(this.status);
+}
+
+class DeleteBook extends BookDetailsEvent {
+  const DeleteBook();
+}