Add config.db volume mapping to docker-compose

- Map config.db to host for database persistence
- Ensures user configurations, traders, and AI models persist across container restarts
- Enables easy backup of configuration database
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: tinkle-community <tinklefund@gmail.com>

docker-compose.yml

@@ -10,6 +10,7 @@ services:
       - "${NOFX_BACKEND_PORT:-8080}:8080"
     volumes:
       - ./config.json:/app/config.json:ro
+      - ./config.db:/app/config.db
       - ./decision_logs:/app/decision_logs
       - /etc/localtime:/etc/localtime:ro  # Sync host time
     environment: