Fix Express trust proxy for Hugging Face Spaces deployment

crossword-app/backend/src/app.js

@@ -8,6 +8,11 @@ const apiRoutes = require('./routes/api');
 const app = express();
 const PORT = process.env.PORT || 7860;
 
+// Trust proxy for platforms like Hugging Face Spaces, Heroku, etc.
+if (process.env.NODE_ENV === 'production') {
+  app.set('trust proxy', 1);
+}
+
 app.use(helmet());
 
 // CORS configuration