feat: update app icon to match iOS design

- Replace all app icon PNG assets with iOS version
- Remove adaptive icon vector drawables (ic_launcher_foreground.xml, ic_launcher_monochrome.xml)
- Remove adaptive icon configuration (mipmap-anydpi-v26)
- Update background color to #EEEEEE to match iOS
- Use pure PNG icons for consistent appearance across all Android versions

The new icon features a black chevron (>) on light gray background, matching the iOS app design.

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

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

Author: graycreate