Update Task model to include optional fields and adapt factory method

This commit updates the Task model to include optional fields for
'additionalInput' and 'artifacts'. The 'fromMap' factory method is also
adapted to populate these fields if they exist in the JSON response.

This change aligns the Task model with the expected server responses,
making it more flexible and robust.

lib/models/task.dart

@@ -1,10 +1,17 @@
 /// Represents a task or topic the user wants to discuss with the agent.
 class Task {
   final String id;
+  final Map<String, dynamic>? additionalInput;
+  final List<String>? artifacts;
+
   String _title;
 
-  Task({required this.id, required String title})
-      : assert(title.isNotEmpty, 'Title cannot be empty'),
+  Task({
+    required this.id,
+    this.additionalInput,
+    this.artifacts,
+    required String title,
+  })  : assert(title.isNotEmpty, 'Title cannot be empty'),
         _title = title;
 
   String get title => _title;
@@ -17,11 +24,24 @@ class Task {
     }
   }
 
-  // Convert a Map (usually from JSON) to a Task object
+// Convert a Map (usually from JSON) to a Task object
   factory Task.fromMap(Map<String, dynamic> map) {
+    Map<String, dynamic>? additionalInput;
+    List<String>? artifacts;
+
+    if (map['additional_input'] != null) {
+      additionalInput = Map<String, dynamic>.from(map['additional_input']);
+    }
+
+    if (map['artifacts'] != null) {
+      artifacts = List<String>.from(map['artifacts'].map((e) => e.toString()));
+    }
+
     return Task(
-      id: map['id'],
-      title: map['title'],
+      id: map['task_id'],
+      additionalInput: additionalInput,
+      artifacts: artifacts,
+      title: map['input'],
     );
   }