Document host-native release launchers

docs/internal/gotool.md

@@ -15,6 +15,9 @@ requirements, versioned replacements, and checksums. Local replacements resolve
 against their original module directory before relocation. The original main
 module remains a local replacement, including when releasing ReleaseKit itself.
 The private root provides tool resolution independently of consumer vendoring.
+API-only preparation discovers the host target for dependency inspection. The
+returned invocation carries its directory and tool arguments; the CLI's later
+shell command selects the host again when it runs.
 The CLI formats the later invocation using a separate bounded context after
 publication failure. It falls back to a persistent native executable when module
 selection is unavailable or preparation fails, and excludes recognized temporary