Fix trading history: implement proper P&L tracking for closed positions

- Fixed trading history not showing closed positions with positive P&L
- Implemented multi-source trading history fetching (SDK, Data API, DLOB, local DB)
- Added proper P&L calculation using unrealized PnL from Drift positions
- Enhanced TradingHistory component with error handling and sync functionality
- Added manual sync button and better status messages
- Created /api/drift/sync-trades endpoint for manual trade synchronization
- Fixed database integration to properly store and retrieve trades with P&L
- Added comprehensive fallback mechanisms for data fetching
- Improved error messages and user feedback
- Added TRADING_HISTORY_IMPROVEMENTS.md documentation

This addresses the issue where recently closed positions with positive P&L
were not appearing in the trading history section.

app/api/drift/trading-history/route.ts

@@ -10,10 +10,24 @@ export async function GET(request: Request) {
     
     const tradingHistory = await driftTradingService.getTradingHistory(limit)
     
+    // If no trades found, provide helpful message
+    if (tradingHistory.length === 0) {
+      console.log('⚠️ No trading history found')
+      return NextResponse.json({
+        success: true,
+        trades: [],
+        count: 0,
+        message: 'No trading history found. If you recently closed positions, they may take some time to appear in history.'
+      })
+    }
+    
+    console.log(`✅ Successfully fetched ${tradingHistory.length} trades`)
+    
     return NextResponse.json({
       success: true,
       trades: tradingHistory,
-      count: tradingHistory.length
+      count: tradingHistory.length,
+      message: `Found ${tradingHistory.length} trade(s)`
     })
     
   } catch (error: any) {
@@ -22,7 +36,9 @@ export async function GET(request: Request) {
       { 
         success: false, 
         error: error.message,
-        trades: []
+        trades: [],
+        count: 0,
+        message: 'Failed to fetch trading history. Please try again.'
       }, 
       { status: 500 }
     )