Constant DEFAULT_ENRICH_LLM_PARALLELISM 

pub const DEFAULT_ENRICH_LLM_PARALLELISM: u32 = 1;

Default subprocess worker count for enrich when --llm-parallelism is omitted (GAP-SG-141).

1 means serial. The flag is inert under --mode openrouter, where DEFAULT_ENRICH_REST_CONCURRENCY governs fan-out instead.