Initial commit: Expo app with Better Auth integration

- Complete Expo React Native app setup with TypeScript
- Better Auth authentication system integration
- Secure storage implementation for session tokens
- Authentication flow with login/logout functionality
- API client configuration for backend communication
- Responsive UI components with themed styling
- Expo Router navigation setup
- Development configuration and scripts

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

components/haptic-tab.tsx

@@ -0,0 +1,18 @@
+import { BottomTabBarButtonProps } from '@react-navigation/bottom-tabs';
+import { PlatformPressable } from '@react-navigation/elements';
+import * as Haptics from 'expo-haptics';
+
+export function HapticTab(props: BottomTabBarButtonProps) {
+  return (
+    <PlatformPressable
+      {...props}
+      onPressIn={(ev) => {
+        if (process.env.EXPO_OS === 'ios') {
+          // Add a soft haptic feedback when pressing down on the tabs.
+          Haptics.impactAsync(Haptics.ImpactFeedbackStyle.Light);
+        }
+        props.onPressIn?.(ev);
+      }}
+    />
+  );
+}