webrtc_utils

WebRTC support utilities: ICE configuration, metrics, and resource monitors.

Three groups of helpers live here:

• RTC ICE configuration: builders and parsers for RTCPeerConnection-style ICE server JSON, the prioritized get_rtc_configuration resolver, and refresh monitors (HMAC shared-secret, TURN REST, Cloudflare, and a config-file watcher) that push updated credentials through an on_rtc_config callback.
• Metrics: Prometheus gauges/histograms plus an optional per-connection CSV dump of client-reported WebRTC statistics. CSV writes run on a dedicated single-worker thread pool so they preserve row order, never block the event loop, and can be drained deterministically at teardown.
• System/GPU monitors: asyncio polling loops that off-load blocking psutil and GPU queries to worker threads and report through async callbacks.

All periodic loops share the same shutdown idiom: an asyncio.Event waited on with a timeout, so stop() interrupts the sleep immediately instead of waiting out the period.