Announce toasts with VoiceOver (#6250)

* Announce toasts with VoiceOver

Toasts are posted from a separate overlay window and never take
VoiceOver focus, so their text was never spoken. UserIndicatorController
now posts a high priority announcement with the title whenever a toast
with readable text is submitted, including re-submissions of an already
visible toast with the same ID. Modal indicators are not announced.

* Remove empty-title toast announcement check

Co-authored-by: Velin92 <34335419+Velin92@users.noreply.github.com>

* Hide toasts from VoiceOver

The toast title is now announced by UserIndicatorController when the
toast is submitted, so letting VoiceOver also focus the toast itself
would only read the same text twice.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

ElementX/Sources/Other/UserIndicator/UserIndicatorController.swift

@@ -44,6 +44,7 @@ class UserIndicatorController: ObservableObject, UserIndicatorControllerProtocol
         if let index = indicatorQueue.firstIndex(where: { $0.id == indicator.id }) {
             indicatorQueue[index] = indicator
             displayTimes[indicator.id] = .now
+            announceIfNeeded(indicator)
         } else {
             if let delay {
                 delayedIndicators.insert(indicator.id)
@@ -90,5 +91,16 @@ class UserIndicatorController: ObservableObject, UserIndicatorControllerProtocol
         retractIndicatorWithId(indicator.id)
         indicatorQueue.append(indicator)
         displayTimes[indicator.id] = .now
+        announceIfNeeded(indicator)
+    }
+    
+    private func announceIfNeeded(_ indicator: UserIndicator) {
+        guard case .toast = indicator.type else {
+            return
+        }
+        
+        var announcement = AttributedString(indicator.title)
+        announcement.accessibilitySpeechAnnouncementPriority = .high
+        AccessibilityNotification.Announcement(announcement).post()
     }
 }

ElementX/Sources/Other/UserIndicator/UserIndicatorToastView.swift

@@ -33,6 +33,7 @@ struct UserIndicatorToastView: View {
         .background(Color.compound.bgSubtlePrimary)
         .clipShape(RoundedCornerShape(radius: 24.0, corners: .allCorners))
         .shadow(color: .black.opacity(0.1), radius: 6.0, y: 4.0)
+        .accessibilityHidden(true)
         .transition(toastTransition)
     }