Create Task class + tests

lib/models/task.dart

@@ -0,0 +1,41 @@
+/// Represents a task or topic the user wants to discuss with the agent.
+class Task {
+  final int id;
+  String _title;
+
+  Task({required this.id, required String title})
+      : assert(title.isNotEmpty, 'Title cannot be empty'),
+        _title = title;
+
+  String get title => _title;
+
+  set title(String newTitle) {
+    if (newTitle.isNotEmpty) {
+      _title = newTitle;
+    } else {
+      throw ArgumentError('Title cannot be empty.');
+    }
+  }
+
+  // Convert a Map (usually from JSON) to a Task object
+  factory Task.fromMap(Map<String, dynamic> map) {
+    return Task(
+      id: map['id'],
+      title: map['title'],
+    );
+  }
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is Task &&
+          runtimeType == other.runtimeType &&
+          id == other.id &&
+          title == other.title;
+
+  @override
+  int get hashCode => id.hashCode ^ title.hashCode;
+
+  @override
+  String toString() => 'Task(id: $id, title: $title)';
+}