critical: Add maGap to TypeScript interfaces for v9 compatibility

- Added maGap field to RiskCheckRequest interface
- Added maGap field to ExecuteTradeRequest interface
- Health check already enhanced with database connectivity check
- Fixes TypeScript build errors blocking deployment

app/api/trading/execute/route.ts

@@ -29,6 +29,7 @@ export interface ExecuteTradeRequest {
   rsi?: number
   volumeRatio?: number
   pricePosition?: number
+  maGap?: number // V9: MA gap convergence metric
   indicatorVersion?: string // Pine Script version (v5, v6, etc.)
 }