✨(frontend) add sound notification for unread messages

Add togglable audio alerts when new chat messages arrive,
allowing users to customize their notification preferences.

src/frontend/src/features/notifications/MainNotificationToast.tsx

@@ -30,6 +30,7 @@ export const MainNotificationToast = () => {
       participant?: Participant | undefined
     ) => {
       if (!participant || participant.isLocal) return
+      triggerNotificationSound(NotificationType.MessageReceived)
       toastQueue.add(
         {
           participant: participant,
@@ -43,7 +44,7 @@ export const MainNotificationToast = () => {
     return () => {
       room.off(RoomEvent.ChatMessage, handleChatMessage)
     }
-  }, [room])
+  }, [room, triggerNotificationSound])
 
   useEffect(() => {
     const handleDataReceived = (

src/frontend/src/stores/notifications.ts

@@ -14,6 +14,7 @@ const DEFAULT_STATE: State = {
     new Map([
       [NotificationType.ParticipantJoined, true],
       [NotificationType.HandRaised, true],
+      [NotificationType.MessageReceived, true],
     ])
   ),
   soundNotificationVolume: 0.1,