Issue #126 - EUI48 / EUI64 RR support (RFC 7043)

Codeberg issue: https://codeberg.org/DNS-OARC/validns/issues/126

Signed zone carrying EUI48 (TYPE 108) and EUI64 (TYPE 109) RRsets, used to
prove that the EUI wire-format encoding round-trips through DNSSEC. The
signature is the canary: any encoding regression breaks RRSIG verification
immediately.

Zone signed with RSASHA256 so signatures validate on every platform (including
RHEL9 where SHA-1 is disabled by crypto policy). Signing window is 30 days
(2027-01-01 .. 2027-01-31 UTC); the fixture is anchored by -t, so window length
does not affect test stability.

Test-time used by src/t/test.pl: 1800057600 (2027-01-16 00:00 UTC, mid-window).
If regenerate.sh is changed to use a different window, update the -t flag in
test.pl accordingly.

To regenerate:

    cd src/t/issues/126-eui-types
    ./regenerate.sh
