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/models/book_status.dart

@@ -0,0 +1,20 @@
+// Book status enum
+enum BookStatus {
+  reading,
+  done,
+  wantToRead,
+}
+
+// Extension for BookStatus to get display name
+extension BookStatusExtension on BookStatus {
+  String get displayName {
+    switch (this) {
+      case BookStatus.reading:
+        return 'Reading Now';
+      case BookStatus.done:
+        return 'Completed';
+      case BookStatus.wantToRead:
+        return 'Wishlist';
+    }
+  }
+}