The recent-channel resolver copied avatarURLString/providerName and the
recent-playlist resolver copied authorID/providerName - fields that do
not exist in the records the mapper writes - while missing the real
ones (thumbnailURLString, subscriberCount, isVerified, videoCount). As
a result, when the local side won a conflict, those fields silently
kept the older server values.
Also drop the notificationsEnabled preservation in the subscription
resolver: the subscription mapper never writes that field since
notification preferences moved to their own record type.
