nix: stop three defaults from consulting hyperhive.enable

hive-forge's publicUrl and behindGateway, and swarm-controller's
forgeTokenFile, no longer gate their default on
config.services.hyperhive.enable — none of the three has a reader that
depends on hyperhive being enabled to make sense of the value, so the
extra condition only added a hidden coupling. module-eval.nix gains a
centralToggleOff fixture plus four cases asserting each affected
default now resolves identically whether the toggle is on or off.

Refs #4500

nix/host-modules/hive-forge/default.nix

@@ -200,11 +200,7 @@ in
 
     publicUrl = lib.mkOption {
       type = lib.types.nullOr lib.types.str;
-      default =
-        if config.services.hyperhive.enable && deployCfg.forgejo.behindGateway then
-          "https://${cfg.domain}"
-        else
-          null;
+      default = if deployCfg.forgejo.behindGateway then "https://${cfg.domain}" else null;
       defaultText = lib.literalExpression ''
         if behindGateway then "https://''${domain}" else null
       '';
@@ -303,8 +299,7 @@ in
 
     behindGateway = lib.mkOption {
       type = lib.types.bool;
-      default = config.services.hyperhive.enable;
-      defaultText = lib.literalExpression "config.services.hyperhive.enable";
+      default = true;
       description = ''
         Serve forgejo through the hive-gateway nginx as a sub-domain
         vhost (`server_name = cfg.domain`) instead of directly on
@@ -318,8 +313,8 @@ in
         - `gateway.localHostsEntry = true` extends `/etc/hosts` to
           include `cfg.domain → 127.0.0.1` for local dev.
 
-        Defaults to `services.hyperhive.enable` (the gateway always runs
-        alongside hyperhive, so forge auto-routes through it). Set `false`
+        Defaults to `true` (the gateway always runs alongside
+        hyperhive, so forge auto-routes through it). Set `false`
         explicitly to keep forge on the direct port even though the
         gateway is running (e.g. an external git client that doesn't
         traverse the gateway).