fix(backend): add debug logs and remove invalid main.py volume mount

docker-compose.yml

@@ -10,7 +10,6 @@ services:
       - OPENROUTER_API_KEY=${OPENROUTER_API_KEY}
     volumes:
       - ./backend/app:/app/backend/app
-      - ./backend/main.py:/app/backend/main.py
     depends_on:
       db:
         condition: service_healthy