Two small additions to support the M3 handler:
- Peer.Done() — read-only view of the existing 'done' channel,
closed on Close(). Lets external indexes (Handler, admin API)
await peer teardown without polling.
- Peer.AddICECandidate — passthrough so the WHEP PATCH handler
can forward trickle-ICE candidates without reaching into the
PeerConnection directly.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>