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

test/features/web/js_api_test.dart

@@ -0,0 +1,39 @@
+import 'package:dsbridge_flutter/dsbridge_flutter.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:jinzhi_flutter_app/features/web/presentation/js_api.dart';
+
+void main() {
+  test('close invokes the host callback and returns success', () {
+    var closeCalls = 0;
+    final handler = _FakeCompletionHandler();
+    final api = JsApi(onClose: () => closeCalls++);
+
+    api.close(null, handler);
+
+    expect(closeCalls, 1);
+    expect(handler.result, <String, dynamic>{'code': 0, 'message': 'success'});
+  });
+
+  test('coerces JSON mall state payloads', () {
+    expect(
+      coerceMallStateMap(
+        '{"ready":true,"activeTab":"market","canGoBack":false}',
+      ),
+      <String, dynamic>{
+        'ready': true,
+        'activeTab': 'market',
+        'canGoBack': false,
+      },
+    );
+  });
+}
+
+class _FakeCompletionHandler implements CompletionHandler {
+  dynamic result;
+
+  @override
+  void complete([dynamic retValue]) => result = retValue;
+
+  @override
+  void setProgressData(dynamic value) {}
+}