move hiveName to deploy.hive-controller; only a hive host needs a name

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

@@ -706,10 +706,8 @@ in
               # per-host flag is false exactly where this entry is needed.
               webhook.ALLOWED_HOST_LIST = lib.concatStringsSep "," (
                 lib.unique (
-                  [
-                    "external"
-                    hyperhiveDomain
-                  ]
+                  [ "external" ]
+                  ++ lib.optional (hyperhiveDomain != null) hyperhiveDomain
                   ++ lib.optional (swarmDomain != null) swarmDomain
                 )
               );