Fix RCTAppearance setColorScheme crashing CarPlay apps (non-UIWindowScene guard) (#57876)

Summary:
Fixes #57863

`RCTAppearance setColorScheme:` (also reached via `Appearance.setColorScheme()` and `setUserInterfaceStyle`) iterates `RCTSharedApplication().connectedScenes` and reads `scene.windows` on every scene. `connectedScenes` contains `UIScene` objects of any class, and a CarPlay `CPTemplateApplicationScene` is a `UIScene` that does not implement `windows`, so the message send raises `-[CPTemplateApplicationScene windows]: unrecognized selector` and the app aborts.

Fix: guard each scene with `isKindOfClass:[UIWindowScene class]` and skip non-`UIWindowScene` objects before touching `.windows`, mirroring the existing pattern already used in `RCTUtils.mm` (`if (![scene isKindOfClass:[UIWindowScene class]]) { continue; }`).

Note: `RCTDevMenu.mm` `showOnShake` has the same unguarded `for (UIWindowScene *scene ...)` loop and would crash identically in a CarPlay context; left untouched here to keep this fix minimal, but it should get the same guard.

## Changelog:

[IOS] [FIXED] - RCTAppearance.setColorScheme() no longer crashes CarPlay apps when connectedScenes contains a non-UIWindowScene

Pull Request resolved: #57876

Test Plan:
No jest path exists for this code: it is Objective-C, iOS-only, and iOS cannot be built in the Linux environment this PR was developed in. Correctness is by code inspection.

Commands run (in the branch worktree):
- `git diff packages/react-native/React/CoreModules/RCTAppearance.mm` — confirms the only change is the 3-line guard:

```diff
  for (UIWindowScene *scene in RCTSharedApplication().connectedScenes) {
+   if (![scene isKindOfClass:[UIWindowScene class]]) {
+     continue;
+   }
    [windows addObjectsFromArray:scene.windows];
  }
```

- Code inspection of the edited region in full:

```objc
- (void)setColorScheme:(NSString *)style
{
  UIUserInterfaceStyle userInterfaceStyle = [RCTConvert UIUserInterfaceStyle:style];
  NSMutableArray<UIWindow *> *windows = [NSMutableArray new];
  for (UIWindowScene *scene in RCTSharedApplication().connectedScenes) {
    if (![scene isKindOfClass:[UIWindowScene class]]) {
      continue;
    }
    [windows addObjectsFromArray:scene.windows];
  }

  for (UIWindow *window in windows) {
    window.overrideUserInterfaceStyle = userInterfaceStyle;
  }
}
```

The guard makes `setColorScheme` tolerate any non-`UIWindowScene` object in `connectedScenes` by skipping it before the `.windows` message send. `isKindOfClass:` is safe to send to any `UIScene` (all are `NSObject`-derived), so the previously-crashing path is unreachable for CarPlay scenes.

This matches the reporter's production `patch-package` fix that has been field-tested on-device since 2026-08-02.

Reviewed By: cipolleschi

Differential Revision: D115451211

Pulled By: christophpurrer

fbshipit-source-id: ce372259d908355fff077b17df828308f75bffcf

Author: SnowingFox

packages/react-native/React/CoreModules/RCTAppearance.mm

@@ -114,6 +114,9 @@ - (void)setColorScheme:(NSString *)style
   UIUserInterfaceStyle userInterfaceStyle = [RCTConvert UIUserInterfaceStyle:style];
   NSMutableArray<UIWindow *> *windows = [NSMutableArray new];
   for (UIWindowScene *scene in RCTSharedApplication().connectedScenes) {
+    if (![scene respondsToSelector:@selector(windows)]) {
+      continue;
+    }
     [windows addObjectsFromArray:scene.windows];
   }