Add risk management features: implement KillSwitch and StopConditionsGuard; update settings and tests

src/arbitrade/risk/__init__.py

@@ -1,7 +1,15 @@
 """Risk management helpers."""
 
+from arbitrade.risk.kill_switch import KillSwitch
 from arbitrade.risk.loss_limits import LossLimitGuard
 from arbitrade.risk.pre_trade import PreTradeValidator
+from arbitrade.risk.stop_conditions import StopConditionsGuard
 from arbitrade.risk.trade_limits import TradeLimitsGuard
 
-__all__ = ["LossLimitGuard", "TradeLimitsGuard", "PreTradeValidator"]
+__all__ = [
+    "LossLimitGuard",
+    "TradeLimitsGuard",
+    "PreTradeValidator",
+    "KillSwitch",
+    "StopConditionsGuard",
+]