Salvage of the surviving hunk of #3296 by @Mibayy. The PR's gateway
_handle_provider_command hunk targets code removed on main (/provider was
absorbed into /model + /status, which already read model.base_url); the
hermes status mislabel was the remaining live symptom:
_effective_provider_label() only checked the legacy OPENAI_BASE_URL env var,
so a custom endpoint configured canonically in config.yaml still displayed
as OpenRouter.