fix: stale VoiceOver value from async UI updates to Text

[coolsoftwaretyler]

Summary:

This is a targeted fix for #58145, where I observed iOS VoiceOver reading stale values over Text elements that were updated asynchronously (from a setTimeout call).

This patch definitely fixes the issue, but I'm happy to iterate on the design if there are any considerations I haven't taken into account: coolsoftwaretyler/focusissues#1

Maybe related to #49462? Although what I found is that when VoiceOver encountered a failure, it bounced back to the status bar, so it's possible 49462 is some other issue with modals that presents the same failure mode.

Changelog:

Pick one each for the category and type tags:

[IOS] [FIXED] -VoiceOver text readout when changing elements asynchronously

Test Plan:

I built a reproducer and tested this patch with it. To test:

1. Build reproducer (or any app that changes text asynchronously)
2. Install app to physical device (I found the accessibility inspector tool with simulators would paper over the issue, so you need to actually use VoiceOver on a device)
3. Turn on voiceover
4. Navigate through the interface, moving focus through your elements to ensure they work as expected
5. Then use VoiceOver to trigger an async update to some text
6. Move on to any value that was changed by the async update
7. Text will probably be stale, and moving focus no longer works

Before

641000653-9506a48b-7ac4-4728-8908-1148aeb7ad07.mp4

After

ScreenRecording_08-27-2026.10-36-35_1.MP4

[meta-codesync]

@christophpurrer has imported this pull request. If you are a Meta employee, you can view this in D117875865.