ZITADEL: Missing Token Lifecyle Validation (`exp` and `iat`) in JWT IdP Provider

ZITADEL is an open source identity management platform. Prior to 3.4.12 and 4.15.2, ZITADEL's external JWT Identity Provider validation in internal/idp/providers/jwt/session.go skips the maximum token age freshness check when an incoming token omits the iat claim, allowing arbitrarily old tokens from a trusted issuer to pass authentication. This issue is fixed in versions 3.4.12 and 4.15.2.