:persistent_term-backed cache with 24-hour TTL.
Keys are {__MODULE__, cert_url} tuples. Values are {inserted_at, public_key}
tuples. Entries older than 24 hours are evicted on read.
:persistent_term-backed cache with 24-hour TTL.
Keys are {__MODULE__, cert_url} tuples. Values are {inserted_at, public_key}
tuples. Entries older than 24 hours are evicted on read.