sendUpdate
suspend fun sendUpdate(ownerWebId: String, receiverWebId: String, resourceUri: String, mode: ShareMode, resourceType: String? = null, resourceName: String? = null)
Tells a receiver their access level changed. This is an as:Update — deliberately not a re-Offer, so the receiver sees "X updated your access" rather than a fresh share. resourceType / resourceName behave as on sendOffer.