fix(glyph): parallelize mcpjungle server registration

The mcpjungle-register oneshot service registered 9 servers
sequentially, each polling up to 60s for availability. This blocked
nixos-rebuild switch for up to 9 minutes in the worst case.

Run each registration in a background subshell so all servers are
polled concurrently, reducing worst-case wait to 60s.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: stackptr

modules/nixos/llm/mcpjungle.nix

@@ -150,9 +150,16 @@ in {
           fi
         '';
 
-        registrations = lib.concatStringsSep "\n" (lib.mapAttrsToList mkRegistration cfg.servers);
+        mkBackgroundRegistration = name: server: ''
+          (
+            ${mkRegistration name server}
+          ) &
+        '';
+
+        registrations = lib.concatStringsSep "\n" (lib.mapAttrsToList mkBackgroundRegistration cfg.servers);
       in ''
         ${registrations}
+        wait
       '';
     };