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/trading/position-manager.ts

@@ -1202,6 +1202,17 @@ export class PositionManager {
         console.error(`❌ Failed to close ${trade.symbol}:`, errorMsg)
         return
       }
+      
+      // CRITICAL: Check if position needs verification (Nov 16, 2025)
+      // If close transaction confirmed but Drift still shows position open,
+      // DON'T mark as closed yet - keep monitoring until Drift confirms
+      if ((result as any).needsVerification) {
+        console.log(`⚠️ Close transaction confirmed but position still exists on Drift`)
+        console.log(`   Keeping ${trade.symbol} in monitoring until Drift confirms closure`)
+        console.log(`   Ghost detection will handle final cleanup once Drift updates`)
+        // Keep monitoring - ghost detection will eventually see it's closed
+        return
+      }
 
       // Update trade state
       if (percentToClose >= 100) {