malkhut(T3): planner + adversarial counterparties

Planner: Decoupled UCB/UCT simultaneous-move MCTS (sm_mcts.py),
compact action space (action_menu.py), planner alternatives (alternatives.py).
Counterparties: 4+ adversarial agent ecology — ToxicTaker, LatencyArb,
MarketMaker, NoiseTrader + extended: LiquidationFlow, WhaleOrder,
MomentumFollower, SpoofDetector, QueueChaser.

MALKHUT/malkhut/planner/__init__.py

@@ -0,0 +1,2 @@
+from malkhut.planner.sm_mcts import DecoupledUCBPlanner
+from malkhut.planner.action_menu import build_our_actions