Add Windows ARM CI coverage and default to thin launcher on win32/arm64

[Copilot]

Windows ARM runners were not covered in CI, and the action defaulted to the native launcher path on a platform where no native coursier launcher is published. This updates CI coverage and launcher selection so Windows ARM uses the JVM thin launcher by default.

• CI matrix updates (Windows ARM)

  • Added windows-11-arm coverage in .github/workflows/test.yml:
    • test job include matrix (jvm: '21')
    • test-jvm-launchers include matrix (launcher: thin and launcher: assembly)

• Launcher selection behavior

  • Updated src/main.ts launcher resolution:
    • explicit launcher=thin|jvm → thin
    • explicit launcher=assembly → assembly
    • empty launcher on win32 + arm64 → thin (new default)
    • otherwise → native

} else if (launcherInput === '' && isWindowsArm) {
  launcherType = 'thin'
} else {
  launcherType = 'native'
}