[a11y][iOS] Collapsed state ignored by Fabric

Description

On iOS, accessibilityState={{ expanded: true }} works as expected, but accessibilityState={{ expanded: false }} is ignored. That means the collapsed state is not announced by VoiceOver, so users may not know the element can be expanded.

Steps to reproduce

1. Build and run the reproducer on the iOS Simulator.
2. Open Xcode > Open Developer Tool > Accessibility Inspector.
3. Click Select an element to inspect and choose Element 1.
4. Verify Value is expanded.
5. Click Select an element to inspect and choose Element 2.
6. Note Value is None, while it should be collapsed.

React Native Version

0.84.1

Affected Platforms

Runtime - iOS

Areas

Fabric - The New Renderer

Output of npx @react-native-community/cli info

System:
  OS: macOS 26.3.1
  CPU: (12) x64 Intel(R) Core(TM) i5-10600 CPU @ 3.30GHz
  Memory: 74.71 MB / 48.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 22.13.0
    path: /Users/richard/.nvm/versions/node/v22.13.0/bin/node
  Yarn:
    version: 1.22.22
    path: /Users/richard/.nvm/versions/node/v22.13.0/bin/yarn
  npm:
    version: 10.9.2
    path: /Users/richard/.nvm/versions/node/v22.13.0/bin/npm
  Watchman:
    version: 2025.08.04.00
    path: /usr/local/bin/watchman
Managers:
  CocoaPods:
    version: 1.16.2
    path: /Users/richard/.rbenv/shims/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.0
      - iOS 26.0
      - macOS 26.0
      - tvOS 26.0
      - visionOS 26.0
      - watchOS 26.0
  Android SDK:
    API Levels:
      - "31"
      - "33"
      - "34"
      - "35"
      - "36"
    Build Tools:
      - 35.0.0
      - 36.0.0
    System Images:
      - android-31 | Google APIs Intel x86_64 Atom
      - android-33 | Google APIs Intel x86_64 Atom
      - android-33 | Google Play Intel x86_64 Atom
      - android-34 | Google APIs Intel x86_64 Atom
      - android-35 | Google APIs Intel x86_64 Atom
      - android-36 | Google APIs Intel x86_64 Atom
      - android-36 | Google Play Intel x86_64 Atom
    Android NDK: Not Found
IDEs:
  Android Studio: 2025.1 AI-251.26094.121.2512.13840223
  Xcode:
    version: 26.0/17A324
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.16
    path: /usr/bin/javac
  Ruby:
    version: 3.3.4
    path: /Users/richard/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 20.1.0
    wanted: 20.1.0
  react:
    installed: 19.2.3
    wanted: 19.2.3
  react-native:
    installed: 0.84.1
    wanted: 0.84.1
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: true
  newArchEnabled: true

Stacktrace or Logs

N/A

MANDATORY Reproducer

https://github.com/QichenZhu/reproducer-react-native-a11y-state

Screenshots and Videos

リンクされている reproducer から始めて iOS Simulator で実行し、その後 Xcode Accessibility Inspector で Element 1 と Element 2 を検査します。Fabric が iOS で accessibilityState の expanded 値をどのように処理するかを追跡します。accessibilityState={{ expanded: false }} が collapsed として報告され、VoiceOver によって読み上げられれば完了です。