Fixes the package so it builds for every Apple platform, not just macOS.
The CafeExportTool and ComparisonTool example targets imported AppKit unconditionally, which broke the iOS build of the whole-package scheme. Because iOS is a declared platform, Swift Package Index's compatibility build failed and the package didn't appear in the index. Both tool entry points are now guarded with #if os(macOS).
No API or behaviour change to the ShotKit library itself.
.package(url: "https://github.com/birangdev/ShotKit.git", from: "1.0.1")