config: update db credentials to use radionica user

backend/db.py

@@ -6,8 +6,8 @@ from typing import List, Dict, Any, Optional
 # Database configuration (using environment variables for production)
 DB_CONFIG = {
     "host": os.getenv("DB_HOST", "127.0.0.1"),
-    "user": os.getenv("DB_USER", "root"),
-    "password": os.getenv("DB_PASS", ""),
+    "user": os.getenv("DB_USER", "radionica"),
+    "password": os.getenv("DB_PASS", "NY9B9VLifDC9ehZ"),
     "database": os.getenv("DB_NAME", "radionica3d"),
     "port": int(os.getenv("DB_PORT", 3306))
 }