Kotlin Shared Layer:
- Add AppleSignInRequest and AppleSignInResponse models
- Add appleSignIn method to AuthApi and APILayer
- Add appleSignInState and appleSignIn() to AuthViewModel
iOS App:
- Create AppleSignInManager for AuthenticationServices integration
- Create AppleSignInViewModel to coordinate Apple auth flow
- Update LoginView with "Sign in with Apple" button
- Add Sign in with Apple entitlement
- Add accessibility identifier for UI testing
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>