fix(SAC_LSTM_Bot): freeze mirror-twin via eval-mode gate in twin launcher

SACLSTM_EVAL_MODE=1 in SacTwin.sh suppresses all sendTrainingMsg traffic
(lever-4 gate), so the twin never trains — not even in-RAM within a battle.
Required now that the main bot's SACLSTM_SAVE_INTERVAL drops to 1 (v2 relaunch
after checkpoint-cadence diagnosis): without the gate the twin would persist
per-battle drift and stop being the frozen reproducible opponent #54 specifies.

SAC_LSTM_Bot/make_twin.sh

@@ -46,6 +46,11 @@ cat > "$TARGET/SacTwin.sh" <<'EOF'
 DIR="$(cd "$(dirname "$0")" && pwd)"
 export SACLSTM_BOT_JSON="$DIR/SacTwin.json"
 export SACLSTM_WEIGHTS_PATH="$DIR/weights/sac_latest.zip"
+# Freeze contract (#54): the twin is a FROZEN sparring partner, not a
+# co-learner. Eval-mode gate (lever 4) suppresses all sendTrainingMsg traffic,
+# so the twin never trains — not even in-RAM within a battle. Without this,
+# any main-bot checkpoint-interval change would let twin drift accumulate.
+export SACLSTM_EVAL_MODE=1
 exec "$DIR/SAC_LSTM_Bot"
 EOF
 chmod +x "$TARGET/SacTwin.sh" "$TARGET/SAC_LSTM_Bot"