tadpole: Assert that nginx is running when using ppp.pm-site

hosts/tadpole/modules/whib/default.nix

@@ -25,10 +25,11 @@ in
     services.whib-backend = {
       enable = true;
 
+      domain = "api.whib.ppp.pm";
+      useACMEHost = "api.whib.ppp.pm";
+
       backend = {
         signingKey = "$(${pkgs.coreutils}/bin/cat ${config.age.secrets.whib-signing-key.path})";
-        domain = "api.whib.ppp.pm";
-        useACMEHost = "api.whib.ppp.pm";
       };
 
       postgres = {

hosts/test-vm/whib-backend.nix

@@ -16,10 +16,10 @@ in
   config = lib.mkIf enabled {
     services.whib-backend = {
       enable = true;
+      domain = "whib-backend.local";
 
       backend = {
         signingKey = "super-secret-key";
-        domain = "whib-backend.local";
       };
 
       postgres = {