Device.fromJsonMap constructor
Implementation
factory Device.fromJsonMap(Map<String, dynamic> json) {
final txtMap = json['txt'] as Map<String, dynamic>?;
return Device(
name: json['name'] as String,
host: json['host'] as String,
port: (json['port'] as num).toInt(), // ✅ safer parsing
txt: txtMap?.map((k, v) => MapEntry(k.toString(), v.toString())),
);
}