ai.newnal.illi.phone.registerIdentity

Register the caller's Private Phone account (Matrix user ID). Called by a family member from the family app, or by the device with parent 1's device-app session for the account the device calls with. The MXID is taken to belong to the signed-in caller; there is no proof of control. The client creates the account by DID sign-in on a Messaging Node and writes the ILLI enrollment marker first. The Service Agent Node records phoneIdentity in the caller's family spheres and starts room provisioning; calling it again with the same MXID asks for a new provisioning run.