Sends {"type":"user_message","text":"..."} to the ElevenLabs API.
Agent responds with audio + text exactly as if it heard spoken input.
Useful for testing without a microphone and for text-only NPC interactions.
Available in Blueprint on UElevenLabsConversationalAgentComponent.
Compiles cleanly on UE 5.5 Win64.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>