Backport macOS accessibility and TextInput fixes to 0.81-stable, with Paper validation #3135

Summary

Backport the macOS accessibility and TextInput fixes from main (#3136) to 0.81-stable, and finish the Paper (old architecture) work that can't be done on main. main no longer builds the legacy architecture, so the Paper code paths in those commits are untested.

FluentUI React Native applies these fixes to react-native-macos 0.81.9 through a Yarn patch (added in microsoft/fluentui-react-native#4386). It can remove the patch once a 0.81 release contains them.

Commits to backport

Cherry-pick in order. Each commit builds on its own; the last one is optional.

Cherry-pick dry run against 0.81-stable (41bc5d5eb4)

• All native changes apply cleanly.
• Commits 2 and 3 conflict only in packages/rn-tester/js/examples/Accessibility/AccessibilityExample.js. Resolve by adding the two macOS examples to the 0.81 version of the file.

Follow .ai/commands/backport.md: branch 0.81/user/jasonvmo/a11y-fixes, PR titles fix(0.81, macos): …. PRs to 0.81-stable also need a changeset (yarn change:check).

Paper work

These Paper paths changed but could not be exercised on main:

• Read-only: a single-line field with editable={false} is reachable with Tab, its text can be selected and copied, typing is rejected, and it reports AXEnabled = YES. The editable prop reaches RCTUITextField through RCT_REMAP_VIEW_PROPERTY(editable, backedTextInputView.editable, BOOL).
• Disabled: with accessibilityState={{disabled: true}}, single-line and multiline fields are skipped by Tab, refuse click focus, and report AXEnabled = NO. Paper routes the prop through -[RCTBaseTextInputView reactAccessibilityElement] to the new -setAccessibilityState: overrides on RCTUITextField and RCTUITextView.
• Prop removal: removing accessibilityState entirely, not just passing {disabled: false}, re-enables the field. This relies on the new nil handling in RCT_CUSTOM_VIEW_PROPERTY(accessibilityState, …).
• Wrapper focus: RCTBaseTextInputView already returns NO from canBecomeKeyView. However, -[RCTView acceptsFirstResponder] returns focusable || super, and TextInput defaults focusable to true. Check whether clicking the wrapper outside the editor makes it first responder or sends an extra focus event. If it does, add the acceptsFirstResponder override that the Fabric component view now has.
• Roles: accessibilityRole="textbox" reports AXTextField through the new legacy mapping.
• Tab stops: a row of three single-line fields, and a multiline field, each take one Tab press in each direction.
• Appearance: AppKit's disabled styling now applies to disabled fields instead of read-only ones. Check text and placeholder colors.

Fabric re-check on 0.81

Run the RNTester examples added by the commits on the new architecture:

• Accessibility: "Roles from role and accessibilityRole" and "Disabled, selected and expanded state".
• TextInput: "Read-only and disabled" and "Tab stops".

Commit 5 makes the RNTester-macOS window recalculate its key-view loop. Without that change, Tab doesn't move between React Native views in RNTester.

Downstream check

Before tagging the release, point FluentUI React Native at a local build and run yarn storybook smoke --macos --mode stories-and-tests and its --paper variant. Use the selectors components-*--*focus*, components-dropdown--*, components-menu*--* and native-modern-callout--*. With the patch these pass with zero skips: 19/19 shared focus, 8/8 Dropdown, 8/8 Menu and 16/16 Callout. The release should pass the same cases unpatched.