feat: Add input status related API; update synchronization monitoring related API.

lib/src/models/input_status_changed_data.dart

@@ -0,0 +1,24 @@
+class InputStatusChangedData {
+  final String userID;
+  final String conversationID;
+  final List<int>? platformIDs;
+
+  InputStatusChangedData({
+    required this.userID,
+    required this.conversationID,
+    this.platformIDs,
+  });
+
+  InputStatusChangedData.fromJson(Map<String, dynamic> json)
+      : userID = json['userID'],
+        conversationID = json['conversationID'],
+        platformIDs = List<int>.from(json['platformIDs'] ?? []);
+
+  Map<String, dynamic> toJson() {
+    final data = <String, dynamic>{};
+    data['userID'] = userID;
+    data['conversationID'] = conversationID;
+    data['platformIDs'] = platformIDs;
+    return data;
+  }
+}