fix: use clearColor instead of systemBackgroundColor for visionOS (#125)

Author: okwasniewski

packages/react-native/Libraries/AppDelegate/RCTAppDelegate.mm

@@ -113,7 +113,11 @@ - (UIView *)viewWithModuleName:(NSString *)moduleName initialProperties:(NSDicti
                                                                    sizeMeasureMode:RCTSurfaceSizeMeasureModeWidthExact | RCTSurfaceSizeMeasureModeHeightExact];
 
     rootView = (RCTRootView *)surfaceHostingProxyRootView;
+#if TARGET_OS_VISION
+    rootView.backgroundColor = [UIColor clearColor];
+#else
     rootView.backgroundColor = [UIColor systemBackgroundColor];
+#endif
     [self customizeRootView:(RCTRootView *)rootView];
     return rootView;
   }