Function sanitize_session_llm_override 

pub fn sanitize_session_llm_override(
    session_id: &str,
    state: &mut SessionState,
    global_llm_provider: &str,
) -> bool

Sanitize potentially invalid persisted (provider, model) overrides.

This wrapper injects crate::llm_validation::is_model_compatible_with_provider as the concrete model-compatibility validator.

Returns true if any repair was applied.