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>

constants/theme.ts

@@ -0,0 +1,69 @@
+/**
+ * Below are the colors that are used in the app. The colors are defined in the light and dark mode.
+ * There are many other ways to style your app. For example, [Nativewind](https://www.nativewind.dev/), [Tamagui](https://tamagui.dev/), [unistyles](https://reactnativeunistyles.vercel.app), etc.
+ */
+
+import { Platform } from 'react-native';
+
+const tintColorLight = '#0a7ea4';
+const tintColorDark = '#fff';
+
+export const Colors = {
+  light: {
+    text: '#11181C',
+    background: '#fff',
+    tint: tintColorLight,
+    icon: '#687076',
+    tabIconDefault: '#687076',
+    tabIconSelected: tintColorLight,
+    card: '#fff',
+    cardBorder: '#e0e0e0',
+    categoryBadge: '#007AFF',
+    categoryBadgeText: '#fff',
+    tagBadge: '#e0e0e0',
+    tagBadgeText: '#11181C',
+    imagePlaceholder: '#f0f0f0',
+    error: '#ff3b30',
+  },
+  dark: {
+    text: '#ECEDEE',
+    background: '#151718',
+    tint: tintColorDark,
+    icon: '#9BA1A6',
+    tabIconDefault: '#9BA1A6',
+    tabIconSelected: tintColorDark,
+    card: '#1F2223',
+    cardBorder: '#2C2E2F',
+    categoryBadge: '#0A84FF',
+    categoryBadgeText: '#fff',
+    tagBadge: '#2C2E2F',
+    tagBadgeText: '#ECEDEE',
+    imagePlaceholder: '#2C2E2F',
+    error: '#ff453a',
+  },
+};
+
+export const Fonts = Platform.select({
+  ios: {
+    /** iOS `UIFontDescriptorSystemDesignDefault` */
+    sans: 'system-ui',
+    /** iOS `UIFontDescriptorSystemDesignSerif` */
+    serif: 'ui-serif',
+    /** iOS `UIFontDescriptorSystemDesignRounded` */
+    rounded: 'ui-rounded',
+    /** iOS `UIFontDescriptorSystemDesignMonospaced` */
+    mono: 'ui-monospace',
+  },
+  default: {
+    sans: 'normal',
+    serif: 'serif',
+    rounded: 'normal',
+    mono: 'monospace',
+  },
+  web: {
+    sans: "system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif",
+    serif: "Georgia, 'Times New Roman', serif",
+    rounded: "'SF Pro Rounded', 'Hiragino Maru Gothic ProN', Meiryo, 'MS PGothic', sans-serif",
+    mono: "SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', monospace",
+  },
+});