ip-address: misclassification of IPv4-mapped/NAT64 IPv6 addresses can bypass SSRF and trust-boundary checks

Summary Address6's special-property checks misclassify IPv4-mapped ::ffff:0:0/96 and NAT64 well-known 64:ff9b::/96 IPv6 addresses. These checks classify an address by its IPv6 wrapper rather than by the IPv4 address it embeds, so isLoopback, isLinkLocal, isMulticast, and isUnspecified all return...