feat: 对齐常驻商城与七鱼客服交互

- 同步商城 H5 登录态与原生 token
- 完善商城/原生 tab 切换、动画及返回交互
- 修复七鱼客服键盘避让和状态栏恢复
- 调整开屏跳过按钮与登录入口交互

lib/features/web/presentation/js_api_result.dart

@@ -0,0 +1,19 @@
+import 'dart:convert';
+
+class JsApiResult {
+  const JsApiResult({required this.code, required this.message, this.data});
+
+  const JsApiResult.success() : code = 0, message = 'success', data = null;
+
+  final int code;
+  final String message;
+  final Map<String, dynamic>? data;
+
+  Map<String, dynamic> toMap() => <String, dynamic>{
+    'code': code,
+    'message': message,
+    if (data != null) 'data': data,
+  };
+
+  String toJson() => jsonEncode(toMap());
+}