When `services.hyperhive.gateway.enable` is on (default), the c0re
NixOS module now sets `HIVE_GATEWAY_ENABLED=1` on the service env.
`/api/state` exposes the flag as `gateway_enabled`; the SW4RM tab's
container-row renderer flips three link sites (primary agent-name
link, favicon fetch, `container`-kind nav-strip links) from the
legacy `http://<host>:<port>/` direct TCP shape to same-origin
`/agent/<name>/` URLs — the gateway proxies them to the per-agent
harness via `agent-ports.json` or `agent-sockets.json` (#784 / #815).
Gateway-off deploys keep the direct TCP fallback so local-dev /
operator opt-out keeps working.
`forge`-kind nav-strip links still resolve against `:3000` (separate
sub-domain transition, tracked by `forge.behindGateway`);
`external`-kind links are already absolute.
Mirrors the `HIVE_MATRIX_GUI_ENABLED` env→snapshot-flag pattern.
Docs updated: `docs/web-ui.md::Container row` + new
`docs/gateway.md::Dashboard link shape` section.
fbc41d42a6