feat: 移除 H5 URL 中的品牌参数和缓存参数；更新测试用例以反映更改

lib/main.dart

@@ -15,15 +15,8 @@ const _shellBackground = Color(0xFFF8FBFF);
 const _shellAccent = Color(0xFF0089FF);
 const _shellSubText = Color(0xFF8E9AB0);
 const _resumeCoverDuration = Duration(milliseconds: 700);
-const _noCacheHeaders = {
-  'Cache-Control': 'no-cache, no-store, max-age=0, must-revalidate',
-  'Pragma': 'no-cache',
-  'Expires': '0',
-};
 const _shellBrandingChannel =
     MethodChannel('io.openim.flutter.im_webview_app/shell_branding');
-const _shellWebViewCacheChannel =
-    MethodChannel('io.openim.flutter.im_webview_app/webview_cache');
 const _inspectH5SnapshotScript = r'''
 (() => {
   const toAbsoluteUrl = (value) => {
@@ -468,31 +461,6 @@ class _H5ShellPageState extends State<H5ShellPage> with WidgetsBindingObserver {
     }
   }
 
-  Future<void> _prepareWebViewForFreshLoad() async {
-    await _configureAndroidNoCache();
-    try {
-      await _controller.clearCache();
-    } catch (_) {
-      // Some WebView implementations can reject cache operations during setup.
-    }
-  }
-
-  Future<void> _configureAndroidNoCache() async {
-    final platformController = _controller.platform;
-    if (platformController is! AndroidWebViewController) {
-      return;
-    }
-
-    try {
-      await _shellWebViewCacheChannel.invokeMethod<void>(
-        'configureNoCache',
-        {'webViewId': platformController.webViewIdentifier},
-      );
-    } catch (_) {
-      // Older shells may not expose the native cache channel yet.
-    }
-  }
-
   Future<void> _syncShellBranding() {
     final payload = jsonEncode({
       'name': widget.shellBranding.appName,
@@ -561,12 +529,7 @@ class _H5ShellPageState extends State<H5ShellPage> with WidgetsBindingObserver {
       });
     }
 
-    await _prepareWebViewForFreshLoad();
-
-    await _controller.loadRequest(
-      Uri.parse(url),
-      headers: _noCacheHeaders,
-    );
+    await _controller.loadRequest(Uri.parse(url));
   }
 
   Future<NavigationDecision> _handleNavigationRequest(