refactor: Remove time-based ghost detection, rely purely on Drift API

User feedback: Time-based cleanup (6 hours) too aggressive for legitimate long-running positions.
Drift API is the authoritative source of truth.

Changes:
- Removed cleanupStalePositions() method entirely
- Removed age-based Layer 1 from validatePositions()
- Updated Layer 2: Now verifies with Drift API before removing position
- All ghost detection now uses Drift blockchain as source of truth

Ghost detection methods:
- Layer 2: Queries Drift after 20 failed close attempts
- Layer 3: Queries Drift every 40 seconds during monitoring
- Periodic validation: Queries Drift every 5 minutes

Result: No premature closures, more reliable ghost detection.

lib/trading/position-manager.ts

@@ -237,18 +237,15 @@ export class PositionManager {
     
     console.log('🔍 Validating positions against Drift...')
     
-    // LAYER 1: Database-based age check (doesn't require RPC - always works)
-    await this.cleanupStalePositions()
-    
     try {
       const driftService = getDriftService()
       
-      // If Drift service not ready, use database-only validation
+      // If Drift service not ready, skip this validation cycle
       if (!driftService || !(driftService as any).isInitialized) {
-        console.log('⚠️ Drift service not ready - using database-only validation')
+        console.log('⚠️ Drift service not ready - skipping validation this cycle')
         console.log(`   Positions in memory: ${this.activeTrades.size}`)
-        console.log(`   These will be checked against database on next monitoring cycle`)
-        return // Database cleanup already ran above
+        console.log(`   Will retry on next cycle (5 minutes) or during monitoring (40 seconds)`)
+        return
       }
       
       // Check each tracked trade individually
@@ -283,30 +280,6 @@ export class PositionManager {
     }
   }
 
-  /**
-   * LAYER 1: Database-based stale position cleanup
-   * 
-   * Removes positions from memory that are older than 6 hours
-   * Doesn't require RPC calls - always works even during rate limiting
-   * 
-   * CRITICAL: This prevents ghost accumulation during rate limit death spirals
-   */
-  private async cleanupStalePositions(): Promise<void> {
-    const sixHoursAgo = Date.now() - (6 * 60 * 60 * 1000)
-    
-    for (const [tradeId, trade] of this.activeTrades) {
-      // If position is >6 hours old, it's likely a ghost (max trade duration should be ~2-3 hours)
-      if (trade.entryTime < sixHoursAgo) {
-        console.log(`🔴 STALE GHOST DETECTED: ${trade.symbol} (age: ${Math.floor((Date.now() - trade.entryTime) / 3600000)}h)`)
-        console.log(`   Entry time: ${new Date(trade.entryTime).toISOString()}`)
-        console.log(`   Removing from memory - likely closed externally hours ago`)
-        
-        await this.handleExternalClosure(trade, 'Stale position cleanup (>6h old)')
-        console.log(`✅ Stale ghost cleaned up: ${trade.symbol}`)
-      }
-    }
-  }
-
   /**
    * Handle external closure for ghost position cleanup
    * 
@@ -1178,13 +1151,25 @@ export class PositionManager {
           console.error(`⚠️ Rate limited while closing ${trade.symbol} - will retry on next price update`)
           
           // LAYER 2: Death spiral detector (Nov 15, 2025)
-          // If we've failed to close this position 20+ times (40+ seconds of retries),
-          // force remove from monitoring to prevent infinite rate limit storms
+          // If we've failed 20+ times, check Drift API to see if it's a ghost position
           if (trade.priceCheckCount > 20) {
-            console.log(`🔴 DEATH SPIRAL DETECTED: ${trade.symbol} failed 20+ close attempts`)
-            console.log(`   Forcing removal from monitoring to prevent rate limit exhaustion`)
-            await this.handleExternalClosure(trade, 'Death spiral prevention (20+ failed close attempts)')
-            return
+            try {
+              const driftService = getDriftService()
+              const marketConfig = getMarketConfig(trade.symbol)
+              const position = await driftService.getPosition(marketConfig.driftMarketIndex)
+              
+              // If position doesn't exist on Drift, it's a ghost - remove immediately
+              if (!position || Math.abs(position.size) < 0.01) {
+                console.log(`🔴 LAYER 2: Ghost detected after ${trade.priceCheckCount} failures`)
+                console.log(`   Drift shows position closed/missing - removing from monitoring`)
+                await this.handleExternalClosure(trade, 'Layer 2: Ghost detected via Drift API')
+                return
+              } else {
+                console.log(`   Position verified on Drift (size: ${position.size}) - will keep retrying`)
+              }
+            } catch (checkError) {
+              console.error(`   Could not verify position on Drift:`, checkError)
+            }
           }
           
           // DON'T remove trade from monitoring - let it retry naturally