feat: flutter ui integration

ui/flutter/lib/api/model/task.dart

@@ -0,0 +1,50 @@
+import 'options.dart';
+import 'resource.dart';
+import 'package:json_annotation/json_annotation.dart';
+
+part 'task.g.dart';
+
+enum Status { ready, running, pause, error, done }
+
+@JsonSerializable()
+class Task {
+  String id;
+  Resource res;
+  Options opts;
+  Status status;
+  Progress progress;
+  int size;
+  DateTime createdAt;
+
+  Task({
+    required this.id,
+    required this.res,
+    required this.opts,
+    required this.status,
+    required this.progress,
+    required this.size,
+    required this.createdAt,
+  });
+
+  factory Task.fromJson(Map<String, dynamic> json) => _$TaskFromJson(json);
+
+  Map<String, dynamic> toJson() => _$TaskToJson(this);
+}
+
+@JsonSerializable()
+class Progress {
+  int used;
+  int speed;
+  int downloaded;
+
+  Progress({
+    required this.used,
+    required this.speed,
+    required this.downloaded,
+  });
+
+  factory Progress.fromJson(Map<String, dynamic> json) =>
+      _$ProgressFromJson(json);
+
+  Map<String, dynamic> toJson() => _$ProgressToJson(this);
+}