init: rough companion app stub

lib/domain/models/server_config.dart

@@ -0,0 +1,18 @@
+class ServerConfig {
+  const ServerConfig({required this.host, required this.port});
+
+  final String host;
+  final int port;
+
+  String get wsUrl => 'ws://$host:$port/socket/websocket';
+
+  ServerConfig copyWith({String? host, int? port}) =>
+      ServerConfig(host: host ?? this.host, port: port ?? this.port);
+
+  @override
+  bool operator ==(Object other) =>
+      other is ServerConfig && other.host == host && other.port == port;
+
+  @override
+  int get hashCode => Object.hash(host, port);
+}