Enable Sign in with Apple as a Social Login Option

🔍 Problem Statement

Pelcro does not support Sign in with Apple as a social login option. Apple device users who prefer Apple ID authentication must use email/password or another social login, which reduces conversion on Apple-dominant audiences.

💡 User Story

As a subscriber on an Apple device, I want to sign in with Apple, so that I can create an account or log in with a single tap using my Apple ID.

🎯 Definition of Done (DoD)

A feature is done when:

✔️ Given the Pelcro login/registration form, when a user clicks 'Sign in with Apple', then they are authenticated via Apple's OAuth flow and their account is created or linked — matching the behaviour of existing social login options.