feat: web login page (#1058)

ui/flutter/lib/api/model/login.dart

@@ -0,0 +1,18 @@
+import 'package:json_annotation/json_annotation.dart';
+
+part 'login.g.dart';
+
+@JsonSerializable()
+class LoginReq {
+  String username;
+  String password;
+
+  LoginReq({
+    required this.username,
+    required this.password,
+  });
+
+  factory LoginReq.fromJson(Map<String, dynamic> json) =>
+      _$LoginReqFromJson(json);
+  Map<String, dynamic> toJson() => _$LoginReqToJson(this);
+}

ui/flutter/lib/api/model/login.g.dart

@@ -0,0 +1,17 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'login.dart';
+
+// **************************************************************************
+// JsonSerializableGenerator
+// **************************************************************************
+
+LoginReq _$LoginReqFromJson(Map<String, dynamic> json) => LoginReq(
+      username: json['username'] as String,
+      password: json['password'] as String,
+    );
+
+Map<String, dynamic> _$LoginReqToJson(LoginReq instance) => <String, dynamic>{
+      'username': instance.username,
+      'password': instance.password,
+    };