fix(fabric): fix Text overflow in ScrollView on first render (macOS)

On macOS, the _containerView (NSScrollView's documentView) has
autoresizingMask set so it fills the visible area before React's first
layout pass. However, AppKit's autoresizing corrupts the documentView's
frame by adding the NSClipView's size delta to the container's
dimensions (e.g., during initial tile or window attachment), inflating it
well beyond the correct content size and producing massive horizontal and
vertical overflow on first render.

The fix adds a layoutSubviews override on macOS that resets the
documentView frame to the correct React-managed content size after
AppKit's layout pass (which triggers autoresizing). This corrects the
corruption while preserving the autoresizingMask needed for the
documentView to fill the visible area before React's first updateState.

Fixes #2857

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Saadnajmi

packages/react-native/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm

@@ -184,6 +184,30 @@ - (void)dealloc
 #endif // [macOS]
 }
 
+#if TARGET_OS_OSX // [macOS
+- (void)layoutSubviews
+{
+  [super layoutSubviews];
+
+  // On macOS, the _containerView is the NSScrollView's documentView and has autoresizingMask set so
+  // it fills the visible area before React's first layout pass. However, AppKit's autoresizing can
+  // corrupt the documentView's frame by adding the NSClipView's size delta to the container's
+  // dimensions (e.g., during initial tile or window resize), inflating it well beyond the correct
+  // content size. This produces massive horizontal and vertical overflow on first render.
+  //
+  // After React has set the content size via updateState:, we reset the documentView frame here to
+  // undo any autoresizing corruption. This runs after AppKit's layout (which triggers autoresizing),
+  // so it reliably corrects the frame.
+  if (!CGSizeEqualToSize(_contentSize, CGSizeZero)) {
+    CGRect containerFrame = _containerView.frame;
+    if (!CGSizeEqualToSize(containerFrame.size, _contentSize)) {
+      containerFrame.size = _contentSize;
+      _containerView.frame = containerFrame;
+    }
+  }
+}
+#endif // macOS]
+
 #if TARGET_OS_IOS
 - (void)_registerKeyboardListener
 {