The looksLikeIp helper matched any input the hex/dot character class
accepted — `:::`, `1.2`, `gg:hh::1` all passed. The cf-connecting-ip
flow trusts the header under the env flag and the trusted-proxy XFF
chain forwards the rightmost entry straight to the rate-limiter +
audit log, so a malformed value landed downstream unchanged. Defer to
Node's built-in `isIP` which returns 4 / 6 for valid v4 / v6 and 0
for anything else. Add tests covering the structurally invalid v4 /
v6 / hex shapes plus a positive case for well-formed IPv6.