nx_game_chat_gate.nx

nx_game_chat_gate.nx -- REFEREE for C12 (nx_game_chat, contract gc_room_wire). END-TO-END: builds isolated confs under /tmp/gcgate (game defs + a chatstore conf whose store_root is the fixture), forks the PROMOTED organs, and proves the done-rule: two clients exchange moves and chat through the C1 store with the game's own rules as the referee. THE TOOTH THAT MATTERS IS T10: a move row injected DIRECTLY through nx_chat_store -- bypassing the move verb entirely, the race/hostile-client case -- must be COUNTED AND IGNORED by the replay. A wire anyone can write to is untrusted by construction; the deterministic replay is the authority. Also proven: a full connect-four playthrough to a win, out-of-turn/illegal/full-column/occupied refusals, chat interleaving without disturbing state, the reserved mv: prefix, byte-identical deterministic emits, and the place-mode engine from the ttt conf row (data-driven: two games, one engine, zero game-specific code paths beyond the conf mode). license_tier: ORIGINAL expect_exit: 0