Package calls renders PairUX video calls as truecolor ASCII in the
terminal: `ssh video-<code>@host` joins directly, `ssh video@host` prompts
for a code. Codes are minted by PairUX — the SSH surface never creates
calls, it only joins existing ones.
LiveKit subscriber: joins a PairUX room, takes the first remote VP8 video
track, remuxes RTP into IVF, and has ffmpeg decode + scale it into raw
RGB24 frames sized for the terminal grid.
RouteCode extracts the call code from an SSH username: "video" → "",
"video-abc123" → "abc123". Second return is false when the username is
not a video route at all.