test: add KnowledgeItem model unit tests

test/widget_test.dart

@@ -1,3 +1,4 @@
+import 'package:fabled_app/data/models/knowledge_item.dart';
 import 'package:fabled_app/data/models/note.dart';
 import 'package:flutter_test/flutter_test.dart';
 
@@ -30,4 +31,39 @@ void main() {
       expect(note.noteType, equals('note'));
     });
   });
+
+  group('KnowledgeItem.fromJson', () {
+    test('parses a task item with task fields', () {
+      final json = {
+        'id': 10,
+        'note_type': 'task',
+        'title': 'Do the thing',
+        'body': '',
+        'tags': <dynamic>[],
+        'status': 'todo',
+        'priority': 'high',
+        'due_date': '2025-01-01',
+        'created_at': '2024-01-01T00:00:00',
+        'updated_at': '2024-01-01T00:00:00',
+      };
+      final item = KnowledgeItem.fromJson(json);
+      expect(item.noteType, equals('task'));
+      expect(item.status, equals('todo'));
+      expect(item.priority, equals('high'));
+    });
+
+    test('defaults noteType to note when absent', () {
+      final json = {
+        'id': 11,
+        'title': 'A note',
+        'body': '',
+        'tags': <dynamic>[],
+        'created_at': '2024-01-01T00:00:00',
+        'updated_at': '2024-01-01T00:00:00',
+      };
+      final item = KnowledgeItem.fromJson(json);
+      expect(item.noteType, equals('note'));
+      expect(item.status, isNull);
+    });
+  });
 }