Add Kotlin language support (compiled_lang)

[darkn3rd]

Add Kotlin (https://kotlinlang.org/) as a new language in lessons/compiled_lang/, alongside the existing C++/C#/Go/Java/Rust.

Based on the existing structure (using go/ as the closest reference for the Makefile/Rakefile/psakefile.ps1 shape). Unlike Go, Kotlin compiles to JVM bytecode rather than a native binary, so it needs a JVM present at both build and run time (same needs: java dependency Groovy already uses in scriptbox/config/*.yml), and the Makefile's bin/ output is a runnable .jar (via kotlinc -include-runtime) rather than a native executable - worth deciding whether bin/ holds the .jar directly or a thin java -jar wrapper script per lesson, matching whichever convention reads most consistently against the other languages here.

• New lessons/compiled_lang/kotlin/ directory: Makefile(.win), Rakefile (imports shared testbox.rake), psakefile.ps1, src/ with one .kt file per lesson (a00-o20, ~60 files mirroring Go's set), bin//target/ output dirs
• Add Kotlin to lessons/compiled_lang/{Brewfile,choco.config,cygwin_pkgs.txt,msys2_pkgs.txt,common.mk}
• Add a Kotlin entry to the Compiled Languages area in scriptbox/scripts/verify_commands.rb's AREAS
• Add Kotlin support to scriptbox/config/{ubuntu2204,windows,msys2,cygwin,macos}.yml (needs: java, matching the existing Groovy entries) - package names: sdkman: kotlin (Ubuntu), choco: kotlinc (Windows), brew: kotlin (macOS); MSYS2/Cygwin have no native package and would need a PATH-pointing script to the Windows choco install, matching the existing msys2_groovy_path/cygwin_groovy_path pattern
• lessons/compiled_lang/README.md update

This is a full new-language port (~60 lesson files), so likely worth breaking into smaller PRs rather than one large one.