feat: refresh app icons

[CHOS1N11111]

Summary

• replace the default app icon with the new centered artwork
• replace the iOS dark appearance icon with its matching dark artwork
• preserve the existing asset catalog slots and filenames

Validation

• verified both PNG assets are 1024 x 1024 and opaque RGB
• verified Contents.json resolves both icon files
• visually inspected the resized default and dark outputs
• git diff --check
• Xcode build not run locally because Xcode is unavailable on Windows; macOS CI will compile the asset catalog