Feature: Export schedules via schedule APIs

[Still34]

Title.

Would be awesome if there's a button that exports the selected entry or batch export event entries to any of the native calendar apps on the user's phone.

Both target platforms (iOS, Android) have native APIs that support calendar interactions.

[theimpulson]

Done in Android port of KMP: CCIP-App/CCIP-KMP@98a8ff1