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/scanner/scanner_state.dart

@@ -0,0 +1,42 @@
+import 'package:equatable/equatable.dart';
+
+class ScannerState extends Equatable {
+  final bool isScanning;
+  final bool isProcessing;
+  final Map<String, dynamic>? detectedBookData;
+  final String? errorMessage;
+
+  const ScannerState({
+    this.isScanning = false,
+    this.isProcessing = false,
+    this.detectedBookData,
+    this.errorMessage,
+  });
+
+  factory ScannerState.initial() {
+    return const ScannerState();
+  }
+
+  ScannerState copyWith({
+    bool? isScanning,
+    bool? isProcessing,
+    Map<String, dynamic>? detectedBookData,
+    String? errorMessage,
+    bool clearDetectedBookData = false,
+  }) {
+    return ScannerState(
+      isScanning: isScanning ?? this.isScanning,
+      isProcessing: isProcessing ?? this.isProcessing,
+      detectedBookData: clearDetectedBookData ? null : (detectedBookData ?? this.detectedBookData),
+      errorMessage: errorMessage ?? this.errorMessage,
+    );
+  }
+
+  @override
+  List<Object?> get props => [
+        isScanning,
+        isProcessing,
+        detectedBookData,
+        errorMessage,
+      ];
+}