Credential disclosure via cached authentication requests

Cleartext credential storage in Saleor Commerce Saleor Storefront before 2.10.3 allows local users to read customer emails and passwords. APIProxy authentication and password mutations used Apollo Client's normal caching path, which serialized request variables containing plaintext credentials into browser localStorage instead of applying a no-cache policy. Exploitation requires direct access to an affected browser profile; releases before 2.10.0 retain the cached data after logout, exposing account credentials without affecting service availability.