skydick: disable IPv6 to avoid wg-outbound ULA masquerade timeout
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IPv6 traffic from skydick goes through freedom routing on 10.0.0.1,
which masquerades with ULA fd99:23eb:1682:fe::2 (not globally routable).
This causes nix/cargo downloads to timeout on AAAA records. Skydick has
no IPv6 use cases as a LAN storage server.
Co-Authored-By: Claude Opus 4.6 <[email protected]>
Unified NixOS configuration for skydick (storage server) and
xlab-gateway (lab router). Flat module structure with shared
common/users/ssh modules, agenix secrets, disko, and deploy-rs.
Co-Authored-By: Claude Opus 4.6 <[email protected]>
