XD telephony MVP disconnected

Standalone WebRTC test client. Milestone 1: dial 600 (echo test). Milestone 2: dial a real 7-digit Icelandic number via the Nova trunk.

1. Connect WebSocket server SIP username SIP password

2. Call Destination (600 echo, 601 playback, 700 inbound-sim, callerNNN for browser-to-browser, or 7-digit Icelandic number) idle