Add nm check endpoint which simulates a captive portal

hosts/web-2/ping.nix

@@ -11,13 +11,21 @@
           types { } default_type "text/plain; charset=utf-8";
         '';
       };
-      locations."/nm-check.txt" = {
+      locations."= /nm-check.txt" = {
         return = ''200 "NetworkManager is online\n"'';
         extraConfig = ''
           types { } default_type "text_plain; charset=utf-8";
           add_header Cache-Control "max-age=0, must-revalidate";
         '';
       };
+      # Provide an endpoint to simulate a captive portal redirect for testing
+      locations."= /nm-check-test.txt" = {
+        return = ''302 "http://clerie.de"'';
+        extraConfig = ''
+          types { } default_type "text_plain; charset=utf-8";
+          add_header Cache-Control "max-age=0, must-revalidate";
+        '';
+      };
       locations."/" = {
         return = ''404'';
       };