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/web_back_navigation_test.dart

@@ -0,0 +1,25 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:jinzhi_flutter_app/features/web/application/web_back_navigation.dart';
+
+void main() {
+  test('uses browser history only when it exists', () async {
+    var wentBack = false;
+    expect(
+      await tryGoBackInWebHistory(
+        canGoBack: () async => false,
+        goBack: () async => wentBack = true,
+      ),
+      isFalse,
+    );
+    expect(wentBack, isFalse);
+  });
+
+  test('recognizes DSBridge JavaScript boolean results', () async {
+    expect(
+      await tryGoBackUsingVisibleWebControl(
+        runJavaScriptReturningResult: (_) async => 'true',
+      ),
+      isTrue,
+    );
+  });
+}