a6aca73c67a7b8b0fc6930a5b4546de2231c7655
Add room text chat riding the existing iroh-gossip topic (same layer as the
presence roster). New GossipMessage::Chat { name, text, ts }; the gossip loop
forwards it as RoomEvent::ChatMessage, core relays it to the UI as
UiEvent::ChatMessage, and RoomState::send_chat broadcasts an authored line
(display name from self-state, ms timestamp). CoreCommand::SendChat sends; our
own author is suppressed by the existing self-echo guard, so the UI echoes our
sent line locally instead.
UI: a full-width chat dock along the bottom of the room (the chosen layout) —
bottom-anchored scrollback with per-sender name colouring (green = you), an
input with Enter-to-send + a Send button, history capped at 300 lines. The room
window default grows to 900x760 so the dock doesn't squeeze the controls column.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>