Implement UI screen based on design mockup

[Pawlo7777777]

Description:
Implemented the login and feed screens to match the provided design mockups.

1. Built both screens in React Native using SafeAreaView, Pressable/TouchableOpacity, and StyleSheet for layout and styling.
2. Matched the Instagram wordmark using the Grand Hotel Google Font (via @expo-google-fonts/grand-hotel) loaded through expo-font/expo-splash-screen, applied consistently across both screens.
3. Login screen: email/password inputs, animated Remember Me checkbox, Forgot password link, primary Login button, and a Login with Facebook button, all with proper press/opacity states.
4. Feed screen: horizontal stories list with live badge, post cards with verified badge and country flag, like/comment/share/send actions, and a bottom tab bar.
5. Replaced emoji country flags with flagcdn.com images for cross-platform (Android) rendering consistency.
6. Used StyleSheet.hairlineWidth for the tab bar divider to get a crisp, consistent stroke across device pixel densities.
7. Icons via @expo/vector-icons (Feather).