Stand up the host-side bridge interface + per-agent DNS resolver
ahead of #14 (netns isolation). Mara on #805#11541: "we need it
before #14 so nothing breaks when we switch over". v1 ships the
endpoint live but containers stay on shared host netns — when #14
flips them to private netns the DNS contract is already there.
Shape:
- new `nix/modules/hive-network.nix` with `services.hyperhive.network.*`
options (enable + bridgeName + bridgeIp + bridgePrefixLength +
upstreamDns). Default off. Imported from `hive-c0re.nix`.
- bridge interface via `networking.bridges` (no slave NICs at v1;
per-agent veth pairs attach once #14 lands).
- bridge IP assigned via `networking.interfaces`.
- `networking.firewall.interfaces.<bridge>.allowed{UDP,TCP}Ports =
[ 53 ]` opens the resolver on the bridge interface only —
other interfaces stay closed.
- dnsmasq config added to the existing `hive-gateway` container
(mara on #805:10957: "put the resolver into the gateway container").
Listens only on `bridgeName` + `lo`; authoritative for
`<hive-domain>`, `forge.<hive>`, `matrix.<hive>` answering with
the bridge IP; forwards everything else to upstream.
`resolveLocalQueries = false` keeps the gateway container's own
resolver untouched.
Asserts `services.hyperhive.domain != null` + `gateway.enable =
true` — both required for the resolver to be meaningful.
Docs: new `docs/network.md` covering v1 vs v2 split, container shape
rationale, default addressing, resolver behaviour, firewall posture.
`nix flake check` clean.
ed3b9d853e