Function validate_thread_pools 

fn validate_thread_pools<E>(runtime: &Option<RuntimeConfig>) -> Result<(), E>
where
    E: From<String>,

Validates the declarative thread pool definitions of a runtime config.

Checks ids are non-empty and unique, thread counts are non-zero, real-time priorities and niceness values are in range, and affinity lists are non-empty when present. This is purely a config-level check; pools are built later.