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

Dockerfile

@@ -74,9 +74,14 @@ RUN chmod +x node_modules/.bin/*
 # Expose port
 EXPOSE 3000
 
+# Copy startup script
+COPY docker-entrypoint.sh /usr/local/bin/
+RUN chmod +x /usr/local/bin/docker-entrypoint.sh
+
 # Set environment variables for Puppeteer
 ENV PUPPETEER_SKIP_CHROMIUM_DOWNLOAD=true
 ENV PUPPETEER_EXECUTABLE_PATH=/usr/bin/chromium
+ENV DOCKER_ENV=true
 
-# Start the app (default to development mode)
-CMD ["npm", "run", "dev:docker"]
+# Start the app with cleanup handlers
+ENTRYPOINT ["/usr/local/bin/docker-entrypoint.sh"]