Function register_callback_with_config 

pub async fn register_callback_with_config(
    pool: &PgPool,
    job_id: i64,
    run_lease: i64,
    timeout: Duration,
    config: &CallbackConfig,
) -> Result<Uuid, AwaError>

Register a callback with optional CEL expressions.

When expressions are provided and the cel feature is enabled, each expression is trial-compiled at registration time so syntax errors are caught early.

When the cel feature is disabled and any expression is non-None, returns AwaError::Validation.