Forwarded events carried no origin at all; they read as the forwarder's own
words. buildForwardContent now stamps io.lotus.forwarded (sender, ts,
room_id, event_id; re-forwards keep the original stamp) and the main and
thread timelines render a reply-style header above the message that jumps
to the original when the viewer is in the source room (sender + time only
otherwise — the source room's name is not leaked). Unit-tested; verified
end to end with Playwright (header text, event content, jump, re-forward).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA
