feat: danmaku api (#1530)

lib/pages/danmaku/dnamaku_model.dart

@@ -0,0 +1,27 @@
+sealed class DanmakuExtra {
+  String get mid;
+  Object get id;
+
+  const DanmakuExtra();
+}
+
+class VideoDanmaku extends DanmakuExtra {
+  @override
+  final int id;
+  @override
+  final String mid;
+
+  bool isLike;
+
+  VideoDanmaku({required this.id, required this.mid, this.isLike = false});
+}
+
+class LiveDanmaku extends DanmakuExtra {
+  @override
+  final String id;
+  @override
+  final String mid;
+  final String uname;
+
+  const LiveDanmaku({required this.id, required this.mid, required this.uname});
+}