Add Gunicorn support for production in Vosk service and update requirements

vosk/vosk_service/app_optimized.py

@@ -267,5 +267,11 @@ if __name__ == '__main__':
         app = create_async_app()
         web.run_app(app, host='0.0.0.0', port=5000)
     else:
-        # Run Flask version
-        app.run(host='0.0.0.0', port=5000, threaded=True, processes=4) 
+        # Run Flask version with proper multiprocessing setup
+        # Use Gunicorn for production multiprocessing
+        if os.getenv('USE_GUNICORN', 'false').lower() == 'true':
+            # This will be handled by Gunicorn
+            app.run(host='0.0.0.0', port=5000)
+        else:
+            # Use threading for development
+            app.run(host='0.0.0.0', port=5000, threaded=True)