add traefik for sab

modules/nixos/server/media.nix

···
     user = "media";
     group = "media";
   };
+
+  services.traefik.dynamicConfigOptions.http = {
+    routers.sab = {
+      entryPoints = [ "websecure" ];
+      rule = "Host(`sab.otter.place`)";
+      service = "sab";
+      tls.certResolver = "letsencrypt";
+    };
+
+    services.sab.loadBalancer.servers = [
+      { url = "http://localhost:8080"; }
+    ];
+  };
 }