Function rate_index_name_and_currency 

fn rate_index_name_and_currency(code: &str) -> (String, String)

Resolves any rate index (overnight or term) by code to its curve name — the projection-namespace key ("SOFR", "EURIBOR"), panicking on a wiring error (caught by the registry round-trip test). The projection-curve key and ISO currency of any rate index (overnight or term), resolved by code. The currency is not recoverable from the name — "SOFR" does not say USD — so a template that needs both takes both from one lookup.