add base path setting

docker-compose.yml

@@ -21,6 +21,7 @@ services:
       ADMIN_PASSWORD: ${ADMIN_PASSWORD}
       SECRET_KEY: ${SECRET_KEY}
       COOKIE_SECURE: ${COOKIE_SECURE:-false}
+      BASE_PATH: ${BASE_PATH:-}
     ports: ["${BIND_ADDR:-127.0.0.1}:${HOST_PORT:-8888}:8000"]   # BIND_ADDR: this host's Tailscale IP, never 0.0.0.0. HOST_PORT: port on the host
 volumes:
   pgdata: