fix(ios): center RNNReactButtonView inside navigation bar platter (#8300)

* fix(ios): add Auto Layout constraints to RNNReactButtonView on iOS 26

On iOS 26 the Liquid Glass navigation bar wraps custom-view bar button
items in several internal layout containers.  Without explicit size
constraints the wrapper views can collapse to zero height after a
pop → tab-switch → tab-switch → push cycle, making the React button
invisible.

- Guard all new logic behind @available(iOS 26.0, *) AND a runtime
  check for UIDesignRequiresCompatibility (compatibility mode disables
  Liquid Glass and uses the legacy view hierarchy)
- Set translatesAutoresizingMaskIntoConstraints = NO
- Add width/height constraints at UILayoutPriorityDefaultHigh
- Update constraints in didMountComponentsWithRootTag: after sizeToFit

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(ios): center RNNReactButtonView inside navigation bar platter

On iOS 26 the internal _UITAMICAdaptorView wrapper is wider than the
React button content and UIKit pins the custom view to the leading edge.

Apply a one-time horizontal CGAffineTransform in layoutSubviews to
center the view. Guarded by @available(iOS 26.0, *) and
UIDesignRequiresCompatibility check.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: IsaacIsrael

ios/RNNReactButtonView.mm

@@ -1,6 +1,11 @@
 #import "RNNReactButtonView.h"
+#import <React/RCTSurface.h>
 
-@implementation RNNReactButtonView
+@implementation RNNReactButtonView {
+    NSLayoutConstraint *_widthConstraint;
+    NSLayoutConstraint *_heightConstraint;
+    BOOL _didCenter;
+}
 
 - (instancetype)initWithHost:(RCTHost *)host
                   moduleName:(NSString *)moduleName
@@ -10,15 +15,67 @@ - (instancetype)initWithHost:(RCTHost *)host
          reactViewReadyBlock:(RNNReactViewReadyCompletionBlock)reactViewReadyBlock {
     self = [super initWithHost:host moduleName:moduleName initialProperties:initialProperties eventEmitter:eventEmitter sizeMeasureMode:convertToSurfaceSizeMeasureMode(RCTRootViewSizeFlexibilityWidthAndHeight) reactViewReadyBlock:reactViewReadyBlock];
     [host.surfacePresenter addObserver:self];
-    self.backgroundColor = UIColor.clearColor;
+    self.backgroundColor = [UIColor clearColor];
+
+    if (@available(iOS 26.0, *)) {
+        if (![self designRequiresCompatibility]) {
+            self.translatesAutoresizingMaskIntoConstraints = NO;
+            _widthConstraint = [self.widthAnchor constraintEqualToConstant:0];
+            _heightConstraint = [self.heightAnchor constraintEqualToConstant:0];
+            _widthConstraint.priority = UILayoutPriorityDefaultHigh;
+            _heightConstraint.priority = UILayoutPriorityDefaultHigh;
+            _widthConstraint.active = YES;
+            _heightConstraint.active = YES;
+            _didCenter = NO;
+        }
+    }
 
     return self;
 }
 
+- (BOOL)designRequiresCompatibility {
+    static BOOL checked = NO;
+    static BOOL result = NO;
+    if (!checked) {
+        checked = YES;
+        result = [[[NSBundle mainBundle] objectForInfoDictionaryKey:@"UIDesignRequiresCompatibility"] boolValue];
+    }
+    return result;
+}
+
 - (void)didMountComponentsWithRootTag:(NSInteger)rootTag {
     if (self.surface.rootTag == rootTag) {
         [super didMountComponentsWithRootTag:rootTag];
         [self sizeToFit];
+        if (@available(iOS 26.0, *)) {
+            if (![self designRequiresCompatibility]) {
+                [self updateConstraintsToFitSize];
+            }
+        }
+    }
+}
+
+- (void)updateConstraintsToFitSize {
+    CGSize size = self.frame.size;
+    if (size.width > 0 && size.height > 0) {
+        _widthConstraint.constant = size.width;
+        _heightConstraint.constant = size.height;
+    }
+}
+
+- (void)layoutSubviews {
+    [super layoutSubviews];
+    if (@available(iOS 26.0, *)) {
+        if ([self designRequiresCompatibility]) return;
+        if (!_didCenter && self.superview && self.frame.size.width > 0) {
+            CGFloat wrapperWidth = self.superview.bounds.size.width;
+            CGFloat selfWidth = self.frame.size.width;
+            if (wrapperWidth > selfWidth) {
+                _didCenter = YES;
+                CGFloat tx = (wrapperWidth - selfWidth) / 2.0;
+                self.layer.affineTransform = CGAffineTransformMakeTranslation(tx, 0);
+            }
+        }
     }
 }