Presence chirps now carry the friendly device name, and the engine tracks the
present set as Peers (id/name/source/room). New Engine.present() -> [Peer]
exposes who's online in the room across any network. Both apps poll it and show
a green-dot row of online devices above the feed.
The present set already powered prefer-direct's coverage check; this enriches it
with names and surfaces it. Verified live on macOS: an agent in the room shows
as "● Patrick's NAS".
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>