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.

lib/database/trades.ts

@@ -52,6 +52,12 @@ export interface CreateTradeParams {
   volumeAtEntry?: number
   pricePositionAtEntry?: number
   signalQualityScore?: number
+  // Phantom trade fields
+  status?: string
+  isPhantom?: boolean
+  expectedSizeUSD?: number
+  actualSizeUSD?: number
+  phantomReason?: string
 }
 
 export interface UpdateTradeStateParams {
@@ -124,7 +130,7 @@ export async function createTrade(params: CreateTradeParams) {
         signalSource: params.signalSource,
         signalStrength: params.signalStrength,
         timeframe: params.timeframe,
-        status: 'open',
+        status: params.status || 'open',
         isTestTrade: params.isTestTrade || false,
         // Market context
         expectedEntryPrice: params.expectedEntryPrice,
@@ -136,6 +142,11 @@ export async function createTrade(params: CreateTradeParams) {
         volumeAtEntry: params.volumeAtEntry,
         pricePositionAtEntry: params.pricePositionAtEntry,
         signalQualityScore: params.signalQualityScore,
+        // Phantom trade fields
+        isPhantom: params.isPhantom || false,
+        expectedSizeUSD: params.expectedSizeUSD,
+        actualSizeUSD: params.actualSizeUSD,
+        phantomReason: params.phantomReason,
       },
     })