init: rough companion app stub

lib/domain/models/auth.dart

@@ -0,0 +1,25 @@
+class User {
+  const User({required this.id, required this.username, required this.isAdmin});
+
+  final int id;
+  final String username;
+  final bool isAdmin;
+
+  factory User.fromJson(Map<String, dynamic> json) => User(
+        id: json['id'] as int,
+        username: json['username'] as String,
+        isAdmin: json['is_admin'] as bool,
+      );
+}
+
+class TokenResponse {
+  const TokenResponse({required this.token, required this.user});
+
+  final String token;
+  final User user;
+
+  factory TokenResponse.fromJson(Map<String, dynamic> json) => TokenResponse(
+        token: json['token'] as String,
+        user: User.fromJson(json['user'] as Map<String, dynamic>),
+      );
+}