Add Podman/Docker containerization support

- Dockerfile with Node.js 18 Alpine base image
- Multi-stage build with production dependencies only
- Non-root user for security
- Health checks and proper signal handling
- Volume mounting for persistent database storage
- Docker Compose configuration for easy deployment
- Environment variable support for production config
- Updated README with comprehensive container instructions

Container features:
- Persistent data storage in /app/data volume
- Production-ready configuration
- Security hardened with non-root user
- Health monitoring built-in

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,12 @@
+node_modules
+npm-debug.log
+.git
+.gitignore
+README.md
+.env
+.nyc_output
+coverage
+.DS_Store
+*.log
+etf_trades.db
+cookies.txt