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

cleanup-chromium.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+
+# Cleanup script to kill zombie Chromium processes
+# This should be run periodically or when the application shuts down
+
+echo "🧹 Cleaning up zombie Chromium processes..."
+
+# Kill all defunct chromium processes
+pkill -f "chromium.*defunct" 2>/dev/null
+
+# Kill any remaining chromium processes in the container
+if [ -n "$DOCKER_ENV" ]; then
+    echo "Running in Docker environment, cleaning up container processes..."
+    # In Docker, we need to be more careful about process cleanup
+    ps aux | grep '[c]hromium' | grep -v grep | awk '{print $2}' | xargs -r kill -TERM 2>/dev/null
+    sleep 2
+    ps aux | grep '[c]hromium' | grep -v grep | awk '{print $2}' | xargs -r kill -KILL 2>/dev/null
+else
+    echo "Running in host environment, cleaning up host processes..."
+    pkill -f "chromium" 2>/dev/null
+fi
+
+# Clean up any temporary puppeteer profiles
+rm -rf /tmp/puppeteer_dev_chrome_profile-* 2>/dev/null
+
+echo "✅ Cleanup completed"