added talk notification levels for chats

lib/api/marianumcloud/talk/room/get_room_response.dart

@@ -130,6 +130,12 @@ enum GetRoomResponseObjectParticipantNotificationLevel {
   neverNotify,
 }
 
+extension NotificationLevelApiValue
+    on GetRoomResponseObjectParticipantNotificationLevel {
+  int get apiValue =>
+      _$GetRoomResponseObjectParticipantNotificationLevelEnumMap[this]!;
+}
+
 enum GetRoomResponseObjectMessageActorType {
   @JsonValue('deleted_users')
   deletedUsers,

lib/api/marianumcloud/talk/room/notification_level.dart

@@ -0,0 +1,27 @@
+import 'get_room_response.dart';
+
+typedef NotificationLevel = GetRoomResponseObjectParticipantNotificationLevel;
+
+/// The levels a user can pick in the UI; [NotificationLevel.defaultLevel]
+/// is only ever reported by the server, never chosen.
+const selectableNotificationLevels = [
+  NotificationLevel.alwaysNotify,
+  NotificationLevel.notifyOnMention,
+  NotificationLevel.neverNotify,
+];
+
+extension RoomNotificationLevel on GetRoomResponseObject {
+  /// Resolves "default" the way Spreed does: 1:1 chats notify on every
+  /// message, group chats only on mentions (`default_group_notification`).
+  NotificationLevel get effectiveNotificationLevel {
+    if (notificationLevel != NotificationLevel.defaultLevel) {
+      return notificationLevel;
+    }
+    return type == GetRoomResponseObjectConversationType.oneToOne
+        ? NotificationLevel.alwaysNotify
+        : NotificationLevel.notifyOnMention;
+  }
+
+  bool get isMuted =>
+      effectiveNotificationLevel == NotificationLevel.neverNotify;
+}