4.0.1

Removed

• CocoaPods publishing: 3.0.0 is the last version available as the Punycode pod. 4.0.0 and later are distributed via Swift Package Manager (and Carthage on a best-effort basis). The podspec, the pod lint CI job, and the trunk push in the release workflow are removed.
• Leftover linter configs (.swiftlint.yml, .hound.yml) and .swift-version; linting is enforced by swift-format via CI and fastlane.
• The swift-format script build phase in the Xcode project: it rewrote sources on every build and is incompatible with Xcode's user script sandboxing.

Changed

• Codecov project status now allows a 1% threshold, so coverage noise no longer fails CI.

Fixed

• The framework target now sets APPLICATION_EXTENSION_API_ONLY, so linking the Xcode-built framework (e.g. via Carthage) from an app extension no longer emits a "not safe for use in application extensions" warning (#2). Not applicable to SPM consumers.