Voice AI hands calls over to a second AI agent within the same call

A transfer target can now be another voice agent of the same company. On the EU voice path the call stays on the line: the first agent announces the transfer, the caller optionally hears ringing, the target agent receives a short briefing on the conversation so far (silent or spoken) and takes over without a new greeting. Per target: briefing mode and ring duration. At most two hand-overs per call, one call log, usage booked per segment. Transfers to phone numbers and the previous voice path are unchanged.