Authentication Login

[earamburo]

Summary

Implements user authentication with login/logout functionality and conditional navigation.

Changes

• Authentication: Login screen with username/password validation
• Navigation: React Navigation with AuthStack (Login) and AppStack (Home)
• State Management: React Context with useReducer for auth state
• Storage: AsyncStorage for persisting accessToken and refreshToken
• Styling: Experient-branded form styles and home screen
• Tests: Jest unit tests for LoginScreen and HomeScreen

Auth Flow

1. App launch → checks AsyncStorage for tokens
2. If tokens exist → navigate to Home
3. If no tokens → show Login
4. On login → validate fields → store tokens → navigate to Home
5. On logout → clear tokens → navigate to Login

Testing

Run npm test to execute unit tests.