feat: implement robust browser process cleanup system

- Add cleanup-chromium.sh script for manual zombie process cleanup
- Add docker-entrypoint.sh with signal handlers for graceful shutdown
- Add lib/process-cleanup.ts for automatic cleanup on app termination
- Enhanced forceCleanup() method in tradingview-automation.ts:
  - Individual page closing before browser termination
  - Force kill remaining processes with SIGKILL
  - Reset operation locks after cleanup
- Improved browser launch args to prevent zombie processes:
  - Better crash reporter handling
  - Enhanced background process management
  - Removed problematic --single-process flag
- Updated Dockerfile to use new entrypoint with cleanup handlers
- Set DOCKER_ENV environment variable for container detection
- Add proper signal handling (SIGINT, SIGTERM, SIGQUIT)
- Automatic cleanup of temporary Puppeteer profiles

Resolves zombie Chromium process accumulation issue

lib/tradingview-automation.ts

@@ -124,7 +124,19 @@ export class TradingViewAutomation {
           '--disable-default-apps',
           '--disable-sync',
           '--window-size=1920,1080',
-          '--user-agent=Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36'
+          '--user-agent=Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36',
+          // Additional flags to prevent zombie processes
+          '--disable-background-networking',
+          '--disable-background-timer-throttling',
+          '--disable-backgrounding-occluded-windows',
+          '--disable-breakpad',
+          '--disable-client-side-phishing-detection',
+          '--disable-component-extensions-with-background-pages',
+          '--disable-crash-reporter',
+          '--disable-hang-monitor',
+          '--disable-prompt-on-repost',
+          '--no-crash-upload'
+          // Removed --single-process as it causes issues with Puppeteer
         ]
       })
 
@@ -148,7 +160,24 @@ export class TradingViewAutomation {
     console.log('🧹 Force cleanup: Closing browser and resetting state...')
     try {
       if (this.browser) {
+        // First, close all pages
+        const pages = await this.browser.pages()
+        for (const page of pages) {
+          try {
+            await page.close()
+          } catch (e) {
+            console.log('WARNING: Error closing page:', e)
+          }
+        }
+        
+        // Then close the browser
         await this.browser.close()
+        
+        // Force kill any remaining processes
+        const browserProcess = this.browser.process()
+        if (browserProcess && !browserProcess.killed) {
+          browserProcess.kill('SIGKILL')
+        }
       }
     } catch (e) {
       console.log('WARNING: Error during browser cleanup:', e)
@@ -157,6 +186,7 @@ export class TradingViewAutomation {
     this.browser = null
     this.page = null
     this.isAuthenticated = false
+    this.operationLock = false
     console.log('✅ Cleanup completed')
   }