feat: Expo SDK 52→53 upgrade + full dark mode support
- Upgrade Expo SDK 52→53 (React 18→19, RN 0.76→0.79)
- Remove deprecated packages (native-base, react-native-elements)
- Migrate to @rneui/themed 5.0.0 + modular vector icons
- Fix breaking changes: defaultProps, BackHandler, notifications, key props
- Add Babel plugin for font scaling (replaces Text.defaultProps)
- Configure expo-font for native font preloading
- Add complete dark mode theme system (lib/theme/)
- AppThemeProvider + useThemeColors hook
- Light/dark/fixed color token definitions
- Migrate ~60 files across all screens to use theme colors
- Set userInterfaceStyle to "automatic" for system dark mode
10df37d0a2