feat: 增加媒体权限请求处理逻辑，支持音频和视频权限请求

lib/main.dart

@@ -239,11 +239,13 @@ class _H5ShellPageState extends State<H5ShellPage> with WidgetsBindingObserver {
   }
 
   void _handleShellBridgeMessage(JavaScriptMessage message) {
+    Map<String, dynamic>? payload;
     String? type;
     try {
       final decoded = jsonDecode(message.message);
-      if (decoded is Map<String, dynamic>) {
+      if (decoded is Map) {
-        type = decoded['type'] as String?;
+        payload = Map<String, dynamic>.from(decoded);
+        type = payload['type'] as String?;
       }
     } catch (_) {
       type = message.message;
@@ -252,6 +254,50 @@ class _H5ShellPageState extends State<H5ShellPage> with WidgetsBindingObserver {
     if (type == 'openAppSettings') {
       unawaited(openAppSettings());
     }
+    if (type == 'requestMediaPermissions' && payload != null) {
+      unawaited(_handleMediaPermissionBridgeRequest(payload));
+    }
+  }
+
+  Future<void> _handleMediaPermissionBridgeRequest(
+    Map<String, dynamic> payload,
+  ) async {
+    final requestId = payload['requestId'] as String?;
+    if (requestId == null || requestId.isEmpty) {
+      return;
+    }
+
+    final permissions = <Permission>{};
+    if (payload['audio'] == true) {
+      permissions.add(Permission.microphone);
+    }
+    if (payload['video'] == true) {
+      permissions.add(Permission.camera);
+    }
+
+    final statuses = permissions.isEmpty
+        ? <PermissionStatus>[]
+        : await Future.wait(
+            permissions.map((permission) => permission.request()));
+    final granted = statuses.every(
+      (status) => status.isGranted || status.isLimited,
+    );
+    final permanentlyDenied =
+        statuses.any((status) => status.isPermanentlyDenied);
+    final restricted = statuses.any((status) => status.isRestricted);
+
+    final detail = jsonEncode({
+      'requestId': requestId,
+      'granted': granted,
+      'permanentlyDenied': permanentlyDenied,
+      'restricted': restricted,
+    });
+    final script = '''
+(() => {
+  window.dispatchEvent(new CustomEvent('openim-shell-media-permission-result', { detail: $detail }));
+})();
+''';
+    await _runJavaScriptSafely(script);
   }
 
   void _showTransientShellCover() {