feat(kevin): SA models for bridge audit + backtest persistence

3 tables (kevin_signal_bridge_state, kevin_backtest_runs,
kevin_backtest_trades) all UUID-keyed for consistency with Trade/Position.
KEVIN_STRATEGY_UUID constant pinned for FK joins from Trade.strategy_id.

shared/models/__init__.py

@@ -23,6 +23,14 @@ from shared.models.meet_kevin import (
     KevinAnalysis,
     KevinStockMention,
 )
+from shared.models.meet_kevin_trading import (
+    BridgeStatus,
+    KevinBacktestRun,
+    KevinBacktestRunStatus,
+    KevinBacktestTrade,
+    KevinSignalBridgeState,
+    TriggerSource,
+)
 
 __all__ = [
     "Base",
@@ -57,4 +65,11 @@ __all__ = [
     "KevinTranscript",
     "KevinAnalysis",
     "KevinStockMention",
+    # Meet Kevin trading
+    "BridgeStatus",
+    "KevinBacktestRun",
+    "KevinBacktestRunStatus",
+    "KevinBacktestTrade",
+    "KevinSignalBridgeState",
+    "TriggerSource",
 ]