feat(qr): improve camera error feedback and robustness in QR scanner

- Display prominent, actionable error banners in QR scanner dialog for camera access issues
- Add troubleshooting tips for common camera errors (no device, denied, in use, HTTPS)
- Enhance error handling and logging in WebDialogQRScanner for device detection and permissions
- Use proper type narrowing for promise handling in QRScannerDialog to resolve linter errors
- Improve user experience and clarity when camera access fails or is unavailable

src/services/QRScanner/WebDialogQRScanner.ts

@@ -28,26 +28,79 @@ export class WebDialogQRScanner implements QRScannerService {
 
   async requestPermissions(): Promise<boolean> {
     try {
-      const stream = await navigator.mediaDevices.getUserMedia({ video: true });
-      stream.getTracks().forEach((track) => track.stop());
+      // First check if we have any video devices
+      const devices = await navigator.mediaDevices.enumerateDevices();
+      const videoDevices = devices.filter(device => device.kind === 'videoinput');
+      
+      if (videoDevices.length === 0) {
+        logger.error('No video devices found');
+        throw new Error('No camera found on this device');
+      }
+
+      // Try to get a stream with specific constraints
+      const stream = await navigator.mediaDevices.getUserMedia({
+        video: {
+          facingMode: 'environment',
+          width: { ideal: 1280 },
+          height: { ideal: 720 }
+        }
+      });
+      
+      // Stop the test stream immediately
+      stream.getTracks().forEach(track => track.stop());
       return true;
     } catch (error) {
-      logger.error("Error requesting camera permissions:", {
-        error: error instanceof Error ? error.message : String(error),
-        stack: error instanceof Error ? error.stack : undefined,
+      const wrappedError = error instanceof Error ? error : new Error(String(error));
+      logger.error('Error requesting camera permissions:', {
+        error: wrappedError.message,
+        stack: wrappedError.stack,
+        name: wrappedError.name
       });
-      return false;
+
+      // Provide more specific error messages
+      if (wrappedError.name === 'NotFoundError' || wrappedError.name === 'DevicesNotFoundError') {
+        throw new Error('No camera found on this device');
+      } else if (wrappedError.name === 'NotAllowedError' || wrappedError.name === 'PermissionDeniedError') {
+        throw new Error('Camera access denied. Please grant camera permission and try again');
+      } else if (wrappedError.name === 'NotReadableError' || wrappedError.name === 'TrackStartError') {
+        throw new Error('Camera is in use by another application');
+      } else {
+        throw new Error(`Camera error: ${wrappedError.message}`);
+      }
     }
   }
 
   async isSupported(): Promise<boolean> {
+    try {
     // Check for secure context first
     if (!window.isSecureContext) {
-      logger.warn("Camera access requires HTTPS (secure context)");
+        logger.warn('Camera access requires HTTPS (secure context)');
+        return false;
+      }
+
+      // Check for camera API support
+      if (!navigator.mediaDevices || !navigator.mediaDevices.getUserMedia) {
+        logger.warn('Camera API not supported in this browser');
+        return false;
+      }
+
+      // Check if we have any video devices
+      const devices = await navigator.mediaDevices.enumerateDevices();
+      const hasVideoDevices = devices.some(device => device.kind === 'videoinput');
+      
+      if (!hasVideoDevices) {
+        logger.warn('No video devices found');
+        return false;
+      }
+
+      return true;
+    } catch (error) {
+      logger.error('Error checking camera support:', {
+        error: error instanceof Error ? error.message : String(error),
+        stack: error instanceof Error ? error.stack : undefined
+      });
       return false;
     }
-    // Then check for camera API support
-    return !!(navigator.mediaDevices && navigator.mediaDevices.getUserMedia);
   }
 
   async startScan(): Promise<void> {