Fix import paths and test issues

- Fixed test file import paths to point to correct Bloc file locations
- Fixed Bloc file import paths for models (../../../models/models.dart)
- Added explicit type annotations to resolve null safety warnings
- Fixed null safety issues in wishlist_bloc_test.dart
- All 70 tests now passing

bookshelf_flutter/lib/main.dart

@@ -1,7 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'bloc/app_bloc.dart';
-import 'screens/home_screen.dart';
+import 'features/home/home_screen.dart';
 
 void main() {
   runApp(const BookshelfApp());