Swift Bundler currently supports specifying an application icon using a single PNG file. With the introduction of Apple's new .icon format generated by Icon Composer, it is now possible to define multi-layered icons with Liquid Glass settings in a single source asset. Xcode can already consume .icon files directly to produce all platform-required icon variants.

Request

Add support in Swift Bundler for supplying a .icon file as the application icon. The build system should:

• Accept a .icon asset in the configuration file as an alternative to .png.
• Integrate the .icon file into the produced app bundle in a way compatible with Apple's current icon pipeline.
• Generate the correct icon resources for macOS and other supported Apple platforms based on the .icon contents, mirroring Xcode's behavior.

Rationale

Supporting the .icon format brings Swift Bundler in line with Apple's updated app icon workflow. This allows developers using Xcode-less pipelines to take advantage of layered icon design, Liquid Glass, and mode-dependent adjustments without maintaining multiple rasterized outputs.