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

Author: okwasniewski

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

@@ -76,7 +76,11 @@ - (UIView *)createRootViewWithBridge:(RCTBridge *)bridge
   BOOL enableFabric = self.fabricEnabled;
   UIView *rootView = RCTAppSetupDefaultRootView(bridge, moduleName, initProps, enableFabric);
 
+#if TARGET_OS_VISION
+  rootView.backgroundColor = [UIColor clearColor];
+#else
   rootView.backgroundColor = [UIColor systemBackgroundColor];
+#endif
 
   return rootView;
 }