Add native tooling/runtime deps to export --json

[kubukoz]

Summary

• Adds a nativeOptions field to export --json output when platform == "Native", containing:
  • scalaNativeVersion — the effective Scala Native version
  • compilerPlugins — implicit compiler plugins (e.g. nscplugin)
  • runtimeDependencies — implicit runtime deps (e.g. javalib, scala3lib)
  • toolingDependencies — packaging-time deps (e.g. scala-native-cli)
• Existing top-level fields (scalaNativeVersion, platform, etc.) are unchanged for backward compatibility
• Non-Native exports (JVM, JS) are unaffected — nativeOptions is absent

Closes #4234

Motivation

Downstream tools like scala-cli-nix need to know the full artifact closure used by scala-cli package to prefetch dependencies for offline builds. Previously, export --json only exposed user-declared dependencies, forcing downstream tools to hardcode knowledge of Scala CLI internals (implicit Native runtime/tooling deps).

Example output

{
  "scalaNativeVersion": "0.5.10",
  "nativeOptions": {
    "scalaNativeVersion": "0.5.10",
    "compilerPlugins": [
      { "groupId": "org.scala-native", "artifactId": { "name": "nscplugin", "fullName": "nscplugin_3.2.2" }, "version": "0.5.10" }
    ],
    "runtimeDependencies": [
      { "groupId": "org.scala-native", "artifactId": { "name": "javalib_native0.5", "fullName": "javalib_native0.5_3" }, "version": "0.5.10" },
      { "groupId": "org.scala-native", "artifactId": { "name": "scala3lib_native0.5", "fullName": "scala3lib_native0.5_3" }, "version": "3.2.2+0.5.10" }
    ],
    "toolingDependencies": [
      { "groupId": "org.scala-native", "artifactId": { "name": "scala-native-cli", "fullName": "scala-native-cli_2.12" }, "version": "0.5.10" }
    ]
  }
}

Test plan

• Existing export json with test scope integration test updated with expected nativeOptions
• JVM and JS exports verified to not include nativeOptions
• Manually tested native binary output against a Scala Native project

🤖 Generated with Claude Code

[kubukoz]

issue: this is duplicated

[kubukoz]

I need to test this out a bit more :)