nx_room_relay_gate.nx

nx_room_relay_gate.nx -- proves the sovereign server-relay core (nx_room_relay): 1) roster lists OTHER live peers in a room (not self), correct ids 2) room isolation -- peers in different rooms never see each other 3) frame update -- re-post replaces a peer's latest frame + seq (no dup slot) 4) staleness -- peers past TTL drop out of the roster 5) neg-control -- a ghost peer that never posted is not found Built nx_cc_sovereign -> nxasm_x86 (no gcc, no .sh). Composes with nx_room_stream. license_tier: ORIGINAL