Function parse_revocation_event 

pub fn parse_revocation_event(
    event: &NostrEvent,
) -> Option<LeaseRevocationContent>

Parse a NostrEvent as a LeaseRevocationContent if its kind matches KIND_LEASE_REVOCATION and the body deserializes cleanly. Returns None for any non-revocation event so the caller can fall through to other dispatch arms without re-parsing.

Pure function — exposed so the standby-side dispatcher can be unit-tested without spinning up the relay pool.