fix: a11y actionable items fixes

[isekovanic]

🎯 Goal

This PR should fix some outstanding a11y issues for screen readers. The prior foundation work (a11y context, useA11yLabel, useAccessibilityAnnouncer, useResolvedModalAccessibilityProps, translation namespace, etc.) shipped the primitives. This PR uses those primitives to fix the surfaces flagged by an audit - polls, message context menus, and bottom sheets.

🛠 Implementation details

Five focused changes, each scoped to one surface:

Poll - actionable rotor (Poll.tsx, new usePollAccessibilityActions/usePollAccessibilityLabel/PollUIStateContext)

• Voting, ending the vote, and "show all options" are now exposed as standard accessibility actions. Screen reader users reach each interaction via the rotor/actions menu instead of having to hunt for the right subelement
• PollUIStateContext carries state across the poll's modals (vote / see results / end vote confirm) so the available action set stays correct as the user navigates (we do this so that we have one source of truth for firing these actions)

Poll & Message - context menu hint

• accessibilityHint='a11y/Double tap and hold to activate contextual menu' on both MessageContent and Poll, so screen reader users know a long-press menu is available before triggering it

Message overlay - open announcement (MessageOverlayHostLayer.tsx)

• One shot announceForAccessibility('Swipe right to go through different actions') when the overlay activates. useRef dedupes so it speaks once per open and resets on close

BottomSheetModal - modal trait + accessible dismiss (BottomSheetModal.tsx)

• Drag handle is now a focusable element labeled "Close" with accessibilityRole='button'
• iOS VoiceOver double tap goes into onAccessibilityTap which goes into onClose
• Android TalkBack double tap goes into accessibilityActions=[{name:'activate'}] + onAccessibilityAction which then goes into onClose as well
• iOS two-finger Z scrub triggers onAccessibilityEscape={onClose}. Android hardware back was already wired through Modal.onRequestClose.
• One shot open announcement, deferred 800ms so VoiceOver's auto focus shift speech ("Close, button") doesn't preempt the announce mid sentence.
• Lifts to every consumer automatically: Reactions detail, "More reactions" emoji picker, Attachment type picker, Image gallery grid view.

Translations

• Five new a11y/* keys (Bottom sheet opened…, Close, Double tap and hold to activate contextual menu, Swipe right to go through different actions, plus the poll action labels) added to all 13 locales.

🎨 UI Changes

iOS

Before	After

Android

Before	After

🧪 Testing

☑️ Checklist

• I have signed the Stream CLA (required)
• PR targets the develop branch
• Documentation is updated
• New code is tested in main example apps, including all possible scenarios
  • SampleApp iOS and Android
  • Expo iOS and Android

[Stream-SDK-Bot]

SDK Size

title	develop	branch	diff	status
js_bundle_size	1802 KB	1814 KB	+12569 B	🔴