Phoenix auth fails for docker compose setup

Running phoenixd setup with [docker-compose.yml](https://github.com/getAlby/hub/blob/master/scripts/linux-x86_64/phoenixd/docker-compose.yml) leads to some issues during authentication:

> {"level":"info","msg":"Launching LN Backend: PHOENIX","time":"2025-02-04T17:40:58Z"}
{"error":"invalid character 'I' looking for beginning of value","level":"error","msg":"Failed to launch LN backend","time":"2025-02-04T17:40:58Z"}
{"level":"error","msg":"Failed to launch LN backend: invalid character 'I' looking for beginning of value","time":"2025-02-04T17:40:58Z"}

Additional context:
https://t.me/getAlby/20713/22896

Start with scripts/linux-x86_64/phoenixd/docker-compose.yml and reproduce the phoenixd setup. Trace the authentication response that produces the invalid character 'I' JSON error, then verify that the Phoenix LN backend launches successfully without the reported authentication failure.

Written by the indexing model from the issue text.