ApiKeyRecord/ApiKeyListItem gain a nullable ExpiresUtc (NULL = never
expires); ApiKeyFailure gains KeyExpired. ApiKeyVerifier rejects a key
whose ExpiresUtc is at-or-before now (inclusive, injected clock), before
the secret comparison. CreateKeyAsync gets an expiresUtc overload; rotate
preserves existing expiry. SQLite schema bumps to v3: a nullable
expires_utc column, added to fresh DBs via CREATE and to existing v1/v2
DBs via an idempotent guarded ALTER — donor v2 gateway-auth.db upgrades
in place, no key invalidated. Version 0.1.3 -> 0.1.4 (not yet published;
nuget push is human-gated). Consumers (HistorianGateway, mxaccessgw) bump
to 0.1.4 to set/enforce expiry. 146 Auth.ApiKeys tests pass.
Joseph Doherty