mara on PR #754: "would it be better to specify full forge domain in
options instead?"
Drops the awkward `cfg.subdomain` label option. Now `cfg.domain` is
the single source of truth for both the forgejo `DOMAIN` setting
(existing semantics) AND the gateway vhost server-name (new).
## Before / after
```nix
# before: separate label + cfg.domain juggling
services.hyperhive.forge.subdomain = "forge"; # → forge.<hive>
services.hyperhive.forge.domain = "localhost"; # unused for vhost
# after: full domain, single option
services.hyperhive.forge.domain = "forge.darkest.space"; # ← used for ROOT_URL + vhost
```
## Default
`cfg.domain` default auto-derives:
- `forge.<services.hyperhive.domain>` when hive-domain is set
- `"localhost"` otherwise (pre-#749 direct-on-port shape)
So the common case (hive-domain set) gets `forge.<hive>` for free,
operators with a bespoke shape (`git.example.com`) set the full
hostname directly.
## Assertions
- `cfg.domain != ""` — empty would render `.<hive>` shaped garbage
in both server_name + /etc/hosts.
- `cfg.behindGateway → gateway.enable` — can't route through a
gateway that isn't running.
(The previous "subdomain = empty" assertion is dropped — that
edge case is gone with the rename.)
## Verified
- default with `hyperhive.domain = "test.local"` → `forge.test.local`,
`ROOT_URL = http://forge.test.local/`, vhost present
- `forge.domain = "git.example.com"` → `git.example.com`,
`ROOT_URL = http://git.example.com/`, vhost = `["_", "git.example.com"]`
- `gateway.enable = false` → `forge.domain` falls back to `localhost`,
`ROOT_URL = http://localhost:3000/`, no gateway vhost
(`behindGateway = false`)
- `/etc/hosts` (when `localHostsEntry = true`) → unique entries for
hive-domain + forge.domain (de-duped via `lib.unique` for the
edge case where forge.domain = hive-domain)
- full container toplevel builds clean
## PR title
(Will fix the PR title separately — still says "/forge/" which is
wrong since the rewrite to sub-domain shape.)
9c27c4076f