Registers an abonnement on the `objecten` kanaal pointing at the existing
webhook sink, writes a RegisterRecord exactly as the ACL does on approval, and
waits for the delivery. That is the whole publish chain in one assertion:
Objecten → its celery worker → NRC → nrc-beat → the callback.
Fails today at the first hop, which is the point:
NRC POST /api/v1/abonnement → 400: {"name":"naam","code":"kanaal_naam",
"reason":"Kanaal met deze naam bestaat niet."}
Also splits S-19b (#150) into #152/#153 in BACKLOG.md — the notification wiring
and the projection re-source are independently deployable (CLAUDE.md §13).
not
dc9ca2ceb2