Scala 3.8 requires JDK 17, standard library now built with Scala 3

Scala 3.8 has been released, delivering major ecosystem updates and paving the way for Scala 3.9 LTS. It now requires JDK 17 or later for all compilation and execution. The standard library is compiled using Scala 3 itself, marking a major technical milestone for the ecosystem. The Scala REPL is distributed as a separate artifact, so projects using the REPL must add an explicit dependency. Language features like Better Fors and runtimeChecked have been stabilized, and several experimental capabilities are available for testing.