nixos: services: homebox: proxy websockets

Should avoid a bunch of error logs, and ensure that e.g: adding a label
does not require a refresh to show it in a list.

modules/nixos/services/homebox/default.nix

@@ -33,6 +33,7 @@ in
     my.services.nginx.virtualHosts = {
       homebox = {
         inherit (cfg) port;
+        websocketsLocations = [ "/api" ];
       };
     };