fix: remove incorrect npm --jobs flag and override zmq dependency

- Removed '--jobs 1' from npm install (was causing npm to try and install a package named '1').
- Added 'zmq' to overrides in package.json to prevent ancient native build failures.

backend/package.json

@@ -16,6 +16,7 @@
   },
   "overrides": {
     "mdns2": "$mdns2",
-    "node-uuid": "^1.4.8"
+    "node-uuid": "^1.4.8",
+    "zmq": "$zmq"
   }
 }