- Deduplicate remote participants by fingerprint in all merge sites
(canonical == raw room name caused double-lookup, doubling every remote participant)
- GlobalRoomInactive now propagates updated participant list to other peers
(hub relay B was not informing A when C's participants left)
- Add 15-second stale presence sweeper that purges remote participants
from peers that stop sending data (safety net for QUIC timeout delays)
- Add @Synchronized to WzpEngine.getStats/stopCall/destroy to prevent
TOCTOU race between stats polling coroutine and engine teardown (SIGSEGV)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>