Resolved TURN server config: relay URL + credentials for a TURN entry in a WebRTC ICE server
list. Kept as a standalone type here (rather than reusing
mecha10_video::webrtc::connection::TurnServerConfig) since mecha10-cli-core
intentionally doesn’t depend on mecha10-video - mecha10-video and the nodes that embed it
(camera, video-streamer) are meant to stay lightweight for robot binaries, the same
“minimal dependencies” rationale mecha10-node-resolver documents for inlining its own copy
of DEFAULT_MECHA10_API_URL instead of depending on this crate.