Function verify_user_password 

pub async fn verify_user_password(
    email: &str,
    password: &str,
) -> Result<Option<VerifiedUser>, ConfigError>

Shared verification helper returning the richer VerifiedUser shape. The SSH daemon uses this directly so it can gate the password path on ssh_enabled.

Errors

Returns Err only on infrastructure failure (DB unavailable). Mismatched credentials resolve to Ok(None) — the single failure mode the caller should pattern-match on.