Request camera permission before QR scanning

Sources/QRScannerView.swift

@@ -98,6 +98,30 @@ class QRScannerWindowController: NSObject, AVCaptureMetadataOutputObjectsDelegat
     
     // 在后台线程初始化摄像头
     private func setupCaptureOnBackground(previewHost: NSView) {
+        // 先检查摄像头权限
+        switch AVCaptureDevice.authorizationStatus(for: .video) {
+        case .notDetermined:
+            AVCaptureDevice.requestAccess(for: .video) { [weak self] granted in
+                if granted {
+                    self?.setupCaptureOnBackground(previewHost: previewHost)
+                } else {
+                    DispatchQueue.main.async {
+                        self?.showError("Camera permission denied")
+                    }
+                }
+            }
+            return
+        case .denied, .restricted:
+            DispatchQueue.main.async { [weak self] in
+                self?.showError("Camera permission denied")
+            }
+            return
+        case .authorized:
+            break
+        @unknown default:
+            break
+        }
+        
         let session = AVCaptureSession()
         session.sessionPreset = .high