- Fixed Ultravox Realtime not surfacing server-side interruption. The server sends a `playback_clear_buffer` message when the user interrupts the bot mid-speech, instructing clients to drop buffered output audio; this was previously unhandled, so `BaseOutputTransport` kept playing the buffered audio and the bot kept talking past the interruption. Ultravox now broadcasts `InterruptionFrame` on `playback_clear_buffer`. This was previously masked by enabling local VAD on the user aggregator, which generated `UserStartedSpeakingFrame` and triggered the aggregator-side interruption path; the fix makes the behavior correct without local VAD as a workaround.