feat: Add phantom trade detection and database tracking

- Detect position size mismatches (>50% variance) after opening
- Save phantom trades to database with expectedSizeUSD, actualSizeUSD, phantomReason
- Return error from execute endpoint to prevent Position Manager tracking
- Add comprehensive documentation of phantom trade issue and solution
- Enable data collection for pattern analysis and future optimization

Fixes oracle price lag issue during volatile markets where transactions
confirm but positions don't actually open at expected size.

prisma/migrations/20251104091741_add_phantom_trade_fields/migration.sql

@@ -0,0 +1,5 @@
+-- AlterTable
+ALTER TABLE "Trade" ADD COLUMN     "actualSizeUSD" DOUBLE PRECISION,
+ADD COLUMN     "expectedSizeUSD" DOUBLE PRECISION,
+ADD COLUMN     "isPhantom" BOOLEAN NOT NULL DEFAULT false,
+ADD COLUMN     "phantomReason" TEXT;