fix(admin_sounds): import jsonify to enable JSON responses in admin sound management routes

app/routes/admin_sounds.py

@@ -1,6 +1,6 @@
 """Admin sound management routes."""
 
-from flask import Blueprint, request
+from flask import Blueprint, jsonify, request
 
 from app.services.decorators import require_admin
 from app.services.error_handling_service import ErrorHandlingService