Function endpoint_matches 

pub fn endpoint_matches(
    spec: &EndpointKind,
    substrate: &str,
    kind: &str,
    entity_type: Option<&str>,
) -> bool

true if spec matches the given substrate + kind + entity_type triple.

Pure and DB-free — exposed so offline consumers (e.g. kkernel kg validate, which parses (substrate, kind, entity_type) straight out of NDJSON with no live record to resolve) can apply the exact same EdgeEndpointRule matching semantics pack_rule_allows uses internally, instead of re-deriving a parallel matcher that could drift out of sync.