feat: Replace blind 2-hour reconnect with error-based health monitoring

User Request: Replace blind 2-hour restart timer with smart monitoring that only restarts when accountUnsubscribe errors actually occur

Changes:
. Health Monitor (NEW):
- Created lib/monitoring/drift-health-monitor.ts
- Tracks accountUnsubscribe errors in 30-second sliding window
- Triggers container restart via flag file when 50+ errors detected
- Prevents unnecessary restarts when SDK healthy

. Drift Client:
- Removed blind scheduleReconnection() and 2-hour timer
- Added interceptWebSocketErrors() to catch SDK errors
- Patches console.error to monitor for accountUnsubscribe patterns
- Starts health monitor after successful initialization
- Removed unused reconnect() method and reconnectTimer field

. Health API (NEW):
- GET /api/drift/health - Check current error count and health status
- Returns: healthy boolean, errorCount, threshold, message
- Useful for external monitoring and debugging

Impact:
- System only restarts when actual memory leak detected
- Prevents unnecessary downtime every 2 hours
- More targeted response to SDK issues
- Better operational stability

Files:
- lib/monitoring/drift-health-monitor.ts (NEW - 165 lines)
- lib/drift/client.ts (removed timer, added error interception)
- app/api/drift/health/route.ts (NEW - health check endpoint)

Testing:
- Health monitor starts on initialization: ✅
- API endpoint returns healthy status: ✅
- No blind reconnection scheduled: ✅

lib/drift/client.ts

@@ -7,6 +7,7 @@
 import { Connection, PublicKey, Keypair } from '@solana/web3.js'
 import { DriftClient, initialize, User, PerpMarkets } from '@drift-labs/sdk'
 import bs58 from 'bs58'
+import { getDriftHealthMonitor } from '../monitoring/drift-health-monitor'
 
 // Manual wallet interface (more compatible than SDK Wallet class)
 interface ManualWallet {
@@ -30,8 +31,6 @@ export class DriftService {
   private driftClient: DriftClient | null = null
   private user: User | null = null
   private isInitialized: boolean = false
-  private reconnectTimer: NodeJS.Timeout | null = null
-  private reconnectIntervalMs: number = 2 * 60 * 60 * 1000 // 2 hours (aggressive - Drift SDK memory leak is severe)
 
   constructor(private config: DriftConfig) {
     // Helius connection for Drift SDK initialization (handles burst subscriptions well)
@@ -172,6 +171,9 @@ export class DriftService {
         // Subscribe to Drift account updates (this makes RPC calls)
         await this.driftClient.subscribe()
         console.log('✅ Drift client subscribed to account updates')
+        
+        // Intercept WebSocket errors for health monitoring
+        this.interceptWebSocketErrors()
 
         // Get user account
         this.user = this.driftClient.getUser()
@@ -180,8 +182,9 @@ export class DriftService {
       this.isInitialized = true
       console.log('✅ Drift service initialized successfully')
       
-      // Start periodic reconnection to prevent memory leaks
-      this.scheduleReconnection()
+      // Start health monitoring (error-based restart instead of blind timer)
+      const monitor = getDriftHealthMonitor()
+      monitor.start()
       
     } catch (error) {
       console.error('❌ Failed to initialize Drift service after retries:', error)
@@ -190,61 +193,24 @@ export class DriftService {
   }
 
   /**
-   * Schedule periodic reconnection to prevent WebSocket memory leaks
-   * Drift SDK accumulates subscriptions over time, causing memory leaks
-   * Periodic reconnection clears old subscriptions and resets memory
+   * Intercept WebSocket errors for health monitoring
    */
-  private scheduleReconnection(): void {
-    // Clear existing timer if any
-    if (this.reconnectTimer) {
-      clearTimeout(this.reconnectTimer)
-    }
-
-    // Schedule reconnection every 2 hours
-    this.reconnectTimer = setTimeout(async () => {
-      try {
-        console.log('🔄 Scheduled reconnection: Clearing WebSocket subscriptions to prevent memory leak...')
-        await this.reconnect()
-        console.log('✅ Scheduled reconnection complete - memory freed')
-      } catch (error) {
-        console.error('❌ Scheduled reconnection failed:', error)
-        // Try to initialize fresh if reconnect fails
-        try {
-          this.isInitialized = false
-          await this.initialize()
-        } catch (reinitError) {
-          console.error('❌ Failed to reinitialize after reconnect failure:', reinitError)
-        }
-      }
-    }, this.reconnectIntervalMs)
-
-    console.log(`⏰ Scheduled reconnection in ${this.reconnectIntervalMs / 1000 / 60 / 60} hours`)
-  }
-
-  /**
-   * Reconnect to Drift Protocol (clears old subscriptions)
-   */
-  private async reconnect(): Promise<void> {
-    console.log('🔄 Reconnecting to Drift Protocol...')
+  private interceptWebSocketErrors(): void {
+    const monitor = getDriftHealthMonitor()
     
-    try {
-      // Unsubscribe from old connections
-      if (this.driftClient) {
-        await this.driftClient.unsubscribe()
-        console.log('✅ Unsubscribed from old Drift connection')
+    // Patch console.error to catch accountUnsubscribe errors
+    const originalConsoleError = console.error
+    console.error = (...args: any[]) => {
+      const errorMessage = args.join(' ')
+      
+      // Detect accountUnsubscribe errors (Drift SDK memory leak symptom)
+      if (errorMessage.includes('accountUnsubscribe error') || 
+          errorMessage.includes('readyState was 2')) {
+        monitor.recordError('accountUnsubscribe')
       }
       
-      // Reset state
-      this.driftClient = null
-      this.user = null
-      this.isInitialized = false
-      
-      // Reinitialize
-      await this.initialize()
-      
-    } catch (error) {
-      console.error('❌ Reconnection failed:', error)
-      throw error
+      // Call original console.error
+      originalConsoleError.apply(console, args)
     }
   }
 
@@ -456,13 +422,6 @@ export class DriftService {
    * Disconnect from Drift
    */
   async disconnect(): Promise<void> {
-    // Clear reconnection timer
-    if (this.reconnectTimer) {
-      clearTimeout(this.reconnectTimer)
-      this.reconnectTimer = null
-      console.log('⏰ Cleared reconnection timer')
-    }
-    
     if (this.driftClient) {
       await this.driftClient.unsubscribe()
       console.log('✅ Drift client disconnected')