critical: Fix position close verification to prevent ghost positions

Problem:
- Close transaction confirmed on-chain BUT Drift state takes 5-10s to propagate
- Position Manager immediately checked position after close → still showed open
- Continued monitoring with stale state → eventually ghost detected
- Database marked 'SL closed' but position actually stayed open for 6+ hours
- Position was UNPROTECTED during this time (no monitoring, no TP/SL backup)

Root Cause:
- Transaction confirmation ≠ Drift internal state updated
- SDK needs time to propagate on-chain changes to internal cache
- Position Manager assumed immediate state consistency

Fix (2-layer verification):
1. closePosition(): After 100% close confirmation, wait 5s then verify
   - Query Drift to confirm position actually gone
   - If still exists: Return needsVerification=true flag
   - Log CRITICAL error with transaction signature

2. Position Manager: Handle needsVerification flag
   - DON'T mark position closed in database
   - DON'T remove from monitoring
   - Keep monitoring until ghost detection sees it's actually closed
   - Prevents premature cleanup with wrong exit data

Impact:
- Prevents 6-hour unmonitored position exposure
- Ensures database exit data matches actual Drift closure
- Ghost detection becomes safety net, not primary close mechanism
- User positions always protected until VERIFIED closed

Files:
- lib/drift/orders.ts: Added 5s wait + position verification after close
- lib/trading/position-manager.ts: Check needsVerification flag before cleanup

Incident: Nov 16, 02:51 - Close confirmed but position stayed open until 08:51

lib/drift/orders.ts

@@ -628,13 +628,44 @@ export async function closePosition(
     console.log(`   Closed notional: $${closedNotional.toFixed(2)}`)
     console.log(`   Realized P&L: $${realizedPnL.toFixed(2)}`)
     
-    // If closing 100%, cancel all remaining orders for this market
+    // If closing 100%, verify position actually closed and cancel remaining orders
     if (params.percentToClose === 100) {
       console.log('🗑️ Position fully closed, cancelling remaining orders...')
       const cancelResult = await cancelAllOrders(params.symbol)
       if (cancelResult.success && cancelResult.cancelledCount! > 0) {
         console.log(`✅ Cancelled ${cancelResult.cancelledCount} orders`)
       }
+      
+      // CRITICAL: Verify position actually closed on Drift (Nov 16, 2025)
+      // Transaction confirmed ≠ Drift state updated immediately
+      // Wait 5 seconds for Drift internal state to propagate
+      console.log('⏳ Waiting 5s for Drift state to propagate...')
+      await new Promise(resolve => setTimeout(resolve, 5000))
+      
+      try {
+        const verifyPosition = await driftService.getPosition(marketConfig.driftMarketIndex)
+        if (verifyPosition && Math.abs(verifyPosition.size) >= 0.01) {
+          console.error(`🔴 CRITICAL: Close transaction confirmed BUT position still exists on Drift!`)
+          console.error(`   Transaction: ${txSig}`)
+          console.error(`   Drift size: ${verifyPosition.size}`)
+          console.error(`   This indicates Drift state propagation delay or partial fill`)
+          console.error(`   Position Manager will continue monitoring until Drift confirms closure`)
+          // Return success but flag that monitoring should continue
+          return {
+            success: true,
+            transactionSignature: txSig,
+            closePrice: oraclePrice,
+            closedSize: sizeToClose,
+            realizedPnL,
+            needsVerification: true, // Flag for Position Manager
+          }
+        } else {
+          console.log('✅ Position verified closed on Drift')
+        }
+      } catch (verifyError) {
+        console.warn('⚠️ Could not verify position closure:', verifyError)
+        // Continue anyway - transaction was confirmed
+      }
     }
     
     return {