iOS renders transparent pixels as white, causing a white frame around the
app icon. This fix generates a 1024x1024 RGB PNG (no alpha channel) from
the existing build/icons/sq2160x2160.png source.
Changes:
- Add tools/generate-ios-icon.js script using Sharp to resize and remove alpha
- Add npm script 'generate:ios-icon' for reproducible icon generation
- Update AppIcon-512@2x.png to RGB format (was RGBA)
- Install Sharp as dev dependency for image processing
Icon is now fully opaque with correct brand blue color and white checkmark.
