用户开始录制，拒绝录音录像权限，增加弹窗引导用户前往系统页设置

lib/features/recording/view-model/view_model_recording.dart

@@ -31,6 +31,19 @@ enum ClipboardReadResult {
   invalid,
 }
 
+/// 开始录制所需的相机/麦克风权限检测结果。
+class RecordingRequiredPermissions {
+  const RecordingRequiredPermissions({
+    required this.cameraGranted,
+    required this.microphoneGranted,
+  });
+
+  final bool cameraGranted;
+  final bool microphoneGranted;
+
+  bool get allGranted => cameraGranted && microphoneGranted;
+}
+
 /// 录制页 ViewModel：剪贴板、权限、相机预览与录制流程。
 class RecordingViewModel extends Notifier<RecordingModel> {
   static final _defaultClipboard = ClipboardRecordingModel(
@@ -253,6 +266,30 @@ class RecordingViewModel extends Notifier<RecordingModel> {
     return _galleryPermissions().isEmpty;
   }
 
+  /// 检测并尝试申请相机、麦克风权限，同步更新 session 中的 isMicrophoneGranted。
+  Future<RecordingRequiredPermissions> ensureCameraAndMicrophonePermissions() async {
+    final permissions = await PermissionService.requestMissing([
+      Permission.camera,
+      Permission.microphone,
+    ]);
+
+    final cameraGranted = _isPermissionGranted(permissions[Permission.camera]);
+    final microphoneGranted = _isPermissionGranted(
+      permissions[Permission.microphone],
+    );
+
+    _updateSession((s) => s.copyWith(isMicrophoneGranted: microphoneGranted));
+
+    return RecordingRequiredPermissions(
+      cameraGranted: cameraGranted,
+      microphoneGranted: microphoneGranted,
+    );
+  }
+
+  bool _isPermissionGranted(PermissionStatus? status) {
+    return status?.isGranted == true || status?.isLimited == true;
+  }
+
   /// 开始录制，可选开启勿扰模式。
   Future<void> startRecording({bool enableDoNotDisturb = true}) async {
     final session = state.session;