Contract 0.24.0

collections_edit: curate a collection you own from an agent or a service token. add and remove adjust membership, set replaces it wholesale - the shape an external system syncing a roster wants. Everything in a collection is recorded for as long as it stays there, so adding a tag starts collecting it. Up to 500 tags per call, idempotent, and a malformed tag refuses the whole call rather than silently dropping somebody from a synced roster.