Add persistent storage volume to Docker configuration

- Mount .storage directory from host to container for data persistence
- Update docker-compose.yml with volumes configuration
- Update README.md with volume documentation
- Ensure bookings and settings persist across container restarts

docker-compose.yml

@@ -6,6 +6,8 @@ services:
     env_file:
       - .env
     restart: unless-stopped
+    volumes:
+      - ./.storage:/app/.storage
     healthcheck:
       test: ["CMD", "wget", "--no-verbose", "--tries=1", "--spider", "http://localhost:3000/"]
       interval: 30s